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A Systematic Review and Meta-Analysis of Fecal Contamination and Inadequate Treatment of Packaged Water

  • Ashley R. Williams,

    Affiliation The Water Institute, University of North Carolina, Chapel Hill, NC, United States of America

  • Robert E. S. Bain,

    Affiliations The Water Institute, University of North Carolina, Chapel Hill, NC, United States of America, UNICEF, New York, NY, United States of America

  • Michael B. Fisher,

    Affiliation The Water Institute, University of North Carolina, Chapel Hill, NC, United States of America

  • Ryan Cronk,

    Affiliation The Water Institute, University of North Carolina, Chapel Hill, NC, United States of America

  • Emma R. Kelly,

    Affiliation The Water Institute, University of North Carolina, Chapel Hill, NC, United States of America

  • Jamie Bartram

    jbartram@email.unc.edu

    Affiliation The Water Institute, University of North Carolina, Chapel Hill, NC, United States of America

A Systematic Review and Meta-Analysis of Fecal Contamination and Inadequate Treatment of Packaged Water

  • Ashley R. Williams, 
  • Robert E. S. Bain, 
  • Michael B. Fisher, 
  • Ryan Cronk, 
  • Emma R. Kelly, 
  • Jamie Bartram
PLOS
x

Abstract

Background

Packaged water products provide an increasingly important source of water for consumption. However, recent studies raise concerns over their safety.

Objectives

To assess the microbial safety of packaged water, examine differences between regions, country incomes, packaged water types, and compare packaged water with other water sources.

Methods

We performed a systematic review and meta-analysis. Articles published in English, French, Portuguese, Spanish and Turkish, with no date restrictions were identified from online databases and two previous reviews. Studies published before April 2014 that assessed packaged water for the presence of Escherichia coli, thermotolerant or total coliforms were included provided they tested at least ten samples or brands.

Results

A total of 170 studies were included in the review. The majority of studies did not detect fecal indicator bacteria in packaged water (78/141). Compared to packaged water from upper-middle and high-income countries, packaged water from low and lower-middle-income countries was 4.6 (95% CI: 2.6–8.1) and 13.6 (95% CI: 6.9–26.7) times more likely to contain fecal indicator bacteria and total coliforms, respectively. Compared to all other packaged water types, water from small bottles was less likely to be contaminated with fecal indicator bacteria (OR = 0.32, 95%CI: 0.17–0.58) and total coliforms (OR = 0.10, 95%CI: 0.05, 0.22). Packaged water was less likely to contain fecal indicator bacteria (OR = 0.35, 95%CI: 0.20, 0.62) compared to other water sources used for consumption.

Conclusions

Policymakers and regulators should recognize the potential benefits of packaged water in providing safer water for consumption at and away from home, especially for those who are otherwise unlikely to gain access to a reliable, safe water supply in the near future. To improve the quality of packaged water products they should be integrated into regulatory and monitoring frameworks.

Introduction

The consumption of bottled water is a long-standing tradition in many European countries, and in recent decades consumption of bottled water has spread to other upper-middle and high-income countries (UM/HICs) for various reasons including taste, perceived health benefits, convenience, and concerns over the quality of municipal supplies [1,2]. The distrust of municipal supplies has led many consumers to purchase bottled water instead of drinking readily available tap water [3,4]. Some consumers have shifted from drinking other packaged beverages, such as soft drinks, to bottled water due to health concerns [5].

Growth in bottled water consumption has not been limited to UM/HICs. In many low-income and lower-middle-income countries (LICs) a growing number of households are turning to alternative water sources, including packaged water (PW), to meet their drinking water needs [6]. Use of improved drinking water sources has increased globally but according to the Joint Monitoring Programme (JMP) of WHO and UNICEF, 52% of people in developing regions do not have piped water on-premises, with the proportion rising to 82% in least developed countries (WHO/UNICEF 2014). These households collect water from sources outside the household, which results in a loss of time and energy [7]. At least 1.8 billion people use improved sources that are fecally contaminated [8,9]. The phrase ‘drinking water’ normally refers to water used for all domestic purposes including drinking, cooking, bathing, and laundry. However, only a fraction of domestic household water is consumed through drinking and cooking. We use the phrase ‘water for consumption’ to refer specifically to that fraction of drinking water that is consumed.

PW can provide a convenient alternative source of safe water for consumption for those households without continuous and easily accessible water supplies or those who would need to treat and/or carefully store water to ensure safety. Evidence suggests water stored in the home is significantly more contaminated than water at the source [10,11]. The sale of PW in shops, streets, schools, and workplaces offers consumers easy access to a water source for consumption outside the home. A study in Ibadan, Nigeria reported 88% of respondents traveled less than 100 meters to obtain PW [6]. In some areas where piped water is available, problems of intermittent service and water rationing lead households to purchase water from vendors [12]. Inadequate water infrastructure and lack of water access have led to the rapid development of the PW industry in many LICs.

PW is treated or untreated water for consumption that has been packaged in a container, such as a bottle or a plastic bag, which is then delivered to consumers or sold in stores or in the streets. Bottled water typically is divided into natural mineral waters and treated waters, depending on the source. Natural mineral waters originate from an underground source and are characterized by their mineral contents [13]. These are generally bottled at the source and typically do not undergo additional treatment, since they are considered to be free from pathogenic bacteria. PW other than natural mineral waters may come from various sources and are usually subjected to treatment processes by manufacturers to improve the quality of the water. Bottled water can be sold in individual-sized bottles (0.5–5 L) or in larger containers (5–20 L).

In West Africa, an early form of sachet water, referred to as ‘ice water’, consisted of 250–300 mL of water poured into a plastic bag that was hand-tied by the vendor and sold to consumers [6,14]. With the advent of relatively inexpensive turnkey processing machines, the industry largely transitioned from hand-filled bags to automated heat-sealed sachet machines. While larger PW companies have emerged in numerous countries, many producers are cottage industries operated out of apartments or small sheds [12].

With the expansion of the PW industry, some LIC national governments have attempted to regulate the industry, although many lack adequate regulatory and monitoring frameworks to ensure the safety of packaged drinking water products [15,16]. Even in countries with PW regulations, many unregistered producers are able to operate, due to the low barriers to entry and large potential profits [12]. While some manufacturers may adhere to stringent standards of quality, safety, and hygiene, others have been reported to sell untreated water from undeclared sources. Several recent studies have suggested that the microbial and chemical safety of PW products in LIC settings may not meet national or international guidelines [1721]. In UM/HICs, a few recent studies have reported microbial contamination of PW [2224]. Additional concerns have been raised regarding the environmental impacts of PW consumption including plastic waste generation and disposal especially given the limited recycling and municipal solid waste infrastructure in many LICs.

International guidelines for drinking water from the World Health Organization (WHO) recommend that water be free of detectable fecal indicator bacteria (FIB), specifically: E. coli, although thermotolerant coliforms (TTC) are considered an adequate substitute [25]. Other regulatory agencies use the concentration of total coliforms (TC) as a process indictor, in addition to FIB, with the presence of either TC or FIB in drinking water indicating the possible presence of pathogenic organisms due to a water treatment failure or contamination in the distribution system [26]. WHO and the Food and Agriculture Organization of the United Nations created the Codex Alimentarius Commission (CAC), which establishes international standards for food products. According to CAC, microbial standards for bottled water (with the exception of natural mineral waters) are set based on the most recent version of the WHO Guidelines for drinking water quality [27]. Additionally, the International Bottled Water Association (IBWA) publishes its own standards. The IBWA requires products to be free from detectable E. coli and TC in 100 mL of sample [28]. In the IBWA Code of Practice, if a final product tests positive for TC, then additional samples are taken and tested for TC and E. coli, with any subsequent positive samples resulting in a recall of the production lot [28].

Given the large burden of disease associated with inadequate provision of improved water services [29], it is reasonable to assume that the widespread use of PW has the potential to positively impact human health. However, the extent of the protective effect is unknown and is likely to be context-specific depending on the safety of other available water sources. As consumption of PW is increasing in both UM/HICs and LICs, it is important to understand the costs and benefits associated with PW consumption. Focusing on health aspects, the objectives of this study were to review the current literature on the microbial safety of PW, specifically with respect to FIB and TC. We used sub-group analyses to examine the following groups: <5 L bottles and sachets, machine-filled sachets versus hand-filled sachets, geographic regions; countries by income level; and PW and alternative water sources for consumption. Studies using longitudinal and cross-sectional sampling methods were included in the review.

Methods

We conducted a systematic review of studies examining indicators of microbial quality of PW according to PRISMA guidelines for systematic reviews and meta-analysis (S1 Fig) [30]. The review protocol (S1 Text) was registered with PROSPERO (registration number CRD 42014007468).

Inclusion criteria

In order to be eligible for inclusion in the review, studies must have examined the microbial quality of PW and reported findings in English, French, Portuguese, Spanish, or Turkish. PW was defined as water for consumption that is sold in a sealed container, either a sachet or bottle. Studies must have measured TC, TTC, and/or E. coli in at least 10 PW samples and reported the proportion of positive samples (or brands) as well as the total number of samples tested. Studies reporting fewer than 10 samples would likely lead to imprecise estimates of the proportion of samples containing FIB, and this exclusion criteria is consistent with other systematic reviews [11,31]. Studies were excluded if they were unclear which microbial parameter was examined, did not contain primary data, only examined carbonated or flavored PW, or if bacteria had been inoculated into PW. No restrictions were made based on study design or quality. We included both cross-sectional and longitudinal studies, whether or not the PW samples were selected at random, as well as studies whose primary aim was the evaluation of a water quality (diagnostic) test.

Search strategy

We searched five online databases of peer-reviewed journals, African Index Medicus, Biosis Citation Index, Global Health Library, PubMed, and Web of Science without language restriction using ‘water’, terms related to PW, terms related to microbial water quality, and gastrointestinal health outcomes (for full search strategy see S1 Text). The search had no date restrictions. The results were restricted to peer-reviewed journal articles. Searches were conducted between January and April 2014. We identified additional relevant studies through searching the bibliographies of included studies and through Google scholar searches. Relevant papers identified from two previous reviews were also included [12,31].

Eligibility Assessment

Two reviewers (ARW and ERK) independently screened the title and abstract of all identified studies. Full texts were obtained for any article identified as relevant by either reviewer and were examined by both reviewers to assess eligibility for inclusion in the review. A third reviewer (RC) resolved discrepancies at the full text stage. Additional reviewers assisted with full text reviews and data extraction of papers in French (RB), Portuguese (RB), Spanish (MF), and Turkish (AE). If the eligibility was unclear, authors were contacted to provide clarity.

Data extraction

Data were extracted on: study characteristics (country, design, type of PW, total number of samples, total number of brands, sample collection site), study quality parameters (representativeness, randomization, quality assurance/quality control measures), and outcomes (proportion of samples positive for TC, TTC, and/or E. coli).

We extracted the number of samples positive for E. coli, and/or TTC and TC and the total number of samples tested. E. coli, TTC and TC were selected as indicators of contamination due to their widespread use and since they are recommended by international agencies including WHO [25]. When results were presented for various PW brands, we extracted data for each brand. In the case where studies collected water quality samples from other water sources used for consumption, additional data were extracted including the water source type, number of samples, and number of positive samples for each microbial parameter of interest. For studies examining the effects of storage, only the first set of measurements were extracted. Data were extracted for each PW type in studies that examined two or more PW types. Sachets were assumed to be machine-filled unless described as hand-filled. Bottled water was classified as small bottled water if the study did not state the volume.

Data were extracted by one reviewer (ARW) and entered into an extraction table created in Microsoft Excel. Data on study quality and bias were extracted during the data extraction step by one reviewer (ARW). As a quality control, 10% of studies in English (n = 17) were randomly selected for data extraction by a different reviewer (ERK).

Analysis

Extracted data were exported to STATA IC/13.1 (StataCorp, College Station, TX) for random effects meta-regression and meta-analysis with logit transformed [32] proportions of positive samples (or brands) used as the outcome measure. A random effects model was used since heterogeneity in the results of the studies was anticipated. We identified sub-groups a priori in order to explore possible reasons for heterogeneity. The following subgroups were identified (a) bottled water versus sachet water; (b) machine-filled sachets versus hand-filled sachets; (c) location of PW samples along supply chain (manufacturer versus point of sale); (d) country income classification and (e) Millennium Development Goal (MDG) region. PW was classified according to the following types (i) small bottled water (<5 L), (ii) large bottled water (>5 L), (iii) dispensers (>5 L bottles installed on a dispenser), (iv) machine-filled sachets, and (v) hand-filled sachets. Included studies were classified as urban, peri-urban, rural, or national based on the description of the setting. Studies were also categorized by MDG region [33] and by national income level according to the 2014 World Bank classifications (low, lower middle, upper middle, high) [34]. A posteriori we explored differences in microbial quality between PW and other water sources used for consumption, the quality of which was reported in some included studies.

The variance of the transformed proportions was estimated using the inverse of the binomial variance, since it was rarely reported by studies. In order to account for proportions of 0 or 1, a continuity correction of 0.5 was employed for meta-regression [35]. Specifically: for studies in which no samples were positive, 0.5 was substituted for the number of positive samples. Similarly, for studies where all samples were positive, 0.5 was subtracted from the total number of positive samples, which was the denominator. The STATA metareg function was used for meta-regression. Prior to analysis, regional groups were combined as follows: Africa [North Africa, sub-Saharan Africa]; Asia [Southeast Asia, East Asia, South Asia, Oceania, West Asia]; Latin America. PW classification and regional grouping were used in meta-regressions.

To compare the quality of PW and other water sources, we performed meta-analysis using the STATA metan function and calculated random-effects (DerSimonian and Laird) pooled odds ratios of FIB contamination comparing any type of PW and all other water sources used for consumption within a given study. We conducted a sub-group analysis for studies that evaluated tap water in addition to PW. Since the sample sizes were unbalanced, a treatment arm continuity correction (TCC) factor for PW and control arm continuity correction (CCC) factor for other water sources were used in meta-analysis to account for proportions of 0 or 1 [35]. The heterogeneity of the included studies was assessed using the I2 test outlined by Higgins and Thompson [36]. The potential for bias from small study effects was assessed using funnel plots and Egger’s test [37]. Meta regression and meta-analysis were assessed at the 5% significance level. The results from studies that examined multiple PW types were combined during meta-analysis. Randomized and non-randomized studies were included in the meta-regression and the meta-analysis.

Study quality

Articles were assigned a study quality score based on an equal weighting of criteria (one point each) outlined in Table 1 [31]. The impact of including lower quality studies (<4 points) in the review was examined by assessing the sensitivity of the results to exclusion of studies with less than four points.

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Table 1. Criteria used to assess study quality (adapted from Bain et al. 2014b).

https://doi.org/10.1371/journal.pone.0140899.t001

Assessment of bias

In order to assess bias within the studies, we compared the results of representative and non-representative studies, studies that included randomized sampling and those that did not, and compared longitudinal and cross-sectional studies. Longitudinal studies were defined as those that occurred over at least a six-month period with at least two samples collected at different times. We also performed a sensitivity analysis to determine the impact of combining TTC and E. coli as a single outcome measure (FIB).

Results

Search results

A total of 7,545 articles were identified from the five databases and a further 74 articles were identified through bibliography searches, additional hand searching, and previous reviews (Fig 1). A total 4,639 studies were determined to be ineligible during title and abstract screening. At the full text review stage, 242 articles were excluded. The most common reasons for exclusion were that the study did not measure microbial indicators of interest (n = 70), was published in a language other than those included in the review (n = 35), or examined fewer than 10 samples (n = 34). Three studies were excluded because they contained the same dataset as another included paper [3840]. The study with more complete information and data was included in the review. A total of 170 articles representing 172 distinct studies met the inclusion criteria [14,15,17,19,2124,41202].

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Fig 1. PRISMA flowchart.

Results of literature search and screening according to PRISMA flowchart for systematic review screening process (Adapted from Moher et al. 2009).

https://doi.org/10.1371/journal.pone.0140899.g001

Study characteristics

Table 2 summarizes the characteristics of included studies. The majority examined small bottles (n = 96, 56%), while 19% (n = 32), 4% (n = 7), 2% (n = 4), and <1% (n = 1), of studies examined machine-filled sachets, large bottles, dispensers, and hand-filled sachets, respectively. There were 23 (14%) studies that examined two types of PW and 5 (3%) studies that examined three types of PW. Two studies did not specify the type of PW product that was examined [70,170]. Of the included articles, 141 (82%) were published in English, 23 (13%), 6 (3%), 1 (<1%), and 1 (<1%) were published in Portuguese, Spanish, French, and Turkish, respectively. Most studies were from sub-Saharan Africa (31%) or Latin America (23%) (Fig 2). Very few studies were conducted in rural (3%, n = 5) [42,56,102,120,134] or peri-urban settings (2%, n = 4) [161,170,185,200].

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Fig 2. Geographic map of included studies.

Distribution of included studies across Millennium Development Goal regions and country.

https://doi.org/10.1371/journal.pone.0140899.g002

Cross-sectional studies accounted for the majority (n = 146, 85%) of study designs, with only 22 (12%) longitudinal studies included in the review. Five studies collected data in the same setting over multiple years [23,56,80,125,196]. One third (34%, n = 58) of studies reported randomized sample collection procedures, although very few (n = 11, 6%) of those studies described the method of randomization. No study met all nine criteria for study quality and only 14% (n = 29) of included studies received a score of five or higher (S2 Fig). Of the 37 studies examining the microbial quality of sachet water, 19% (n = 7) reported aseptically opening the sachet for analysis either by wiping the exterior of the sachet using ethanol, and/or cutting it using ethanol cleaned scissors, or using a syringe to extract the water from the interior.

Most studies (n = 104, 60%) reported collecting samples from the point of sale (POS), while only 9% (n = 16) of studies collected samples from manufacturers and 6% (n = 10) collected samples from both locations. A minority of studies did not report the location where samples were collected (20%, n = 34). For studies that identified the POS, 41% (n = 46) sampled from retail stores, 4% (n = 5) from street vendors, and 10% (n = 11) collected samples from both retail stores and street vendors.

Three studies examined the presence of contamination on the exterior of sachets [83,85,92]. Egwari et al. (2005) [83] found 45% of sample exteriors were contaminated with E. coli, however, the concentration of E. coli on the exterior was not associated with the concentration of E. coli in the water within the sachet. Ejechi and Ejechi (2008) [85] and Fisher et al. (2015) [92] also observed varying concentrations of contamination on the exteriors of sachets depending on the type of POS (e.g. retail store or street vendor). Both studies found a higher proportion of the exteriors of samples from street vendors to be contaminated with FIB and TC compared to the exteriors of samples from retail stores.

PW quality by type and setting

Meta-regression was used to examine differences in the microbial quality of PW by type and setting (Table 3). Small bottled water was less likely to be contaminated with FIB and TC than other PW types (OR 0.32, 95%CI: 0.17–0.58, p<0.001; OR 0.10, 95% CI 0.05–0.22, p<0.001, respectively). Small bottled water was less likely to be positive for FIB and TC (OR 0.21, 95%CI: 0.10–0.42, p<0.001; OR 0.04, 95%CI: 0.02–0.09, p<0.001, respectively) compared to sachet water (machine-filled and hand-filled). Machine-filled sachets were also less frequently found to contain detectable FIB and TC than hand-filled sachets (OR 0.10, 95%CI: 0.02–0.53, p<0.01; OR 0.04, 95%CI: 0.01–0.26, p<0.001, respectively).

With regards to national income classification, the results show a large difference in the quality of PW from LICs compared to products from UM/HICs with regards to FIB and TC (OR 4.6, 95% CI: 2.6–8.1, p<0.001; OR 13.6, 95%CI: 6.9–26.7, p<0.001, respectively). When only small bottles are considered, the difference remains significant for both FIB and TC (S1 Table, OR 3.4, 95%CI: 1.7–6.9, p<0.001; OR 6.0, 95%CI: 2.9–12.8, p<0.001, respectively).

Regionally, PW products from developed countries were significantly less likely to contain either FIB or TC compared to PW from all other regions (OR 0.12, 95%CI: 0.05–0.27, p<0.001; OR 0.08, 95%CI: 0.03–0.22, p<0.001, respectively). PW from Africa was 3.0 times (95%CI: 1.6–5.5, p<0.01) and 10.7 times (95%CI: 5.1–22.6, p<0.001) more likely to contain FIB and TC, respectively, compared to products from other regions. In contrast, PW from Latin America was less likely than PW from other regions to be contaminated with TC (OR 0.40, 95%CI: 0.16–0.97, p<0.001, respectively), although the results for FIB were not significant (p = 0.350). Furthermore, when examining only small bottles, only the difference between developed countries compared to all other regions remained significant for FIB and TC (S1 Table, OR 0.14, 95%CI: 0.06–0.30, p<0.001; OR 0.20, 95%CI: 0.08–0.48, p<0.001, respectively).

There were only 14 studies that collected both small bottles and sachet samples (excluding hand-filled sachets) (S3 Table). Of those, 12 measured FIB and only seven collected 10 or more samples of each PW type. There were six studies that collected samples of machine-filled sachets and hand-filled sachets, however one study reported results by brand and collected fewer than 10 brands [154].

PW compared to alternative water sources for consumption

Twenty studies examined both PW and other water sources used for consumption, such as tap water, boreholes, hand pumps and/or surface water, within the same geographic area and with 10 or more samples. These studies provide insights into the microbial quality of the PW relative to other available sources of water for consumption.

Fig 3 is a forest plot of the odds of detectable FIB for PW compared to all other water sources used for consumption. PW was found to be significantly less likely to contain detectable FIB compared to other water sources used for consumption within the same area (pooled OR = 0.35, 95%CI: 0.20–0.62, p<0.001). The OR for some studies was greater than one, suggesting that PW may not always less contaminated compared to other water sources. The results vary considerably by study, as shown by the substantial heterogeneity between studies (I2 = 72.3%, p<0.001) [203].

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Fig 3. Forest plot of PW and all other drinking water sources.

Forest plot of the odds ratio of fecal contamination comparing PW and all other drinking water sources.

https://doi.org/10.1371/journal.pone.0140899.g003

The results of the meta-analysis comparing the OR for PW and tap water are shown in Fig 4. Overall, PW was significantly less likely to contain detectable FIB compared to tap water sources (pooled OR = 0.41, 95% CI 0.21–0.79, p<0.01). There was substantial heterogeneity across the studies (I2 = 72.3%, p<0.001) [203]. This could be due to differences in settings, analytical method, and/or season. Seven PW studies had calculated ORs greater than or equal to one, suggesting that while overall PW has a lower odds of contamination than tap water sources, this may not be the case in all study settings.

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Fig 4. Forest plot of PW and tap water sources.

Forest plot of the odds ratio of fecal contamination comparing PW and tap water sources.

https://doi.org/10.1371/journal.pone.0140899.g004

Assessment of Bias

The results of Egger’s test for the meta-analysis of PW and all other water sources used for consumption and PW and tap water sources did not show evidence of small study effects (p = 0.461 and p = 0.756, respectively, S3 and S4 Figs). The results of the meta-regression showed no significant differences between high-quality and low-quality studies, or between representative and non-representative studies and cross-sectional and longitudinal studies, for both FIB and TC (Table 3). However, for TC, results of studies that randomized were significantly more likely to report contamination (p<0.05) compared to studies that did not use randomization. This finding remained significant when considering only small bottles (S1 Table). There was also no statistically significant difference in proportion of contaminated PW samples between studies that reported TTC or E. coli (p = 0.536).

Discussion

A key finding from this review is that PW products are substantially less likely to be contaminated with FIB than alternative water sources for consumption, including tap water. In most studies PW was less likely to contain fecal contamination and may therefore be a safer source of water for consumption than other available sources with respect to microbial quality.

The results of the meta-regression illuminate the large disparity in the microbial quality of PW products between LICs and UM/HICs. PW products from LICs were 4.6 (95%CI: 2.6–8.1) times more likely to contain FIB and 13.6 (95% CI: 6.9–26.7) times more likely to contain TC compared to products from UM/HICs. The statistically significant difference between LICs and UM/HICs remains for both parameters when comparing only small bottles rather than all PW types. Given that many UM/HICs have a longer history with regulating and monitoring PW and packaged foods, the results may suggest that increased regulation and monitoring of PW products lead to an improvement in quality. As many LICs do not have effective regulatory structures in place for PW products, efforts to improve the ability of national governments to properly regulate and monitor these products may accelerate improvements in their safety [12,16]. The presence of TC in finished products indicates inadequate treatment and/or recontamination and suggests that current PW production and process control practices need to be improved in many LICs.

Similarly, PW products from developed nations were significantly less likely to contain FIB or TC compared to other geographic regions. PW products from sub-Saharan Africa were 3.0 (95%CI: 1.6–5.5) and 10.7 (95%CI: 5.1–22.6) times more likely to contain FIB and TC contamination, respectively, compared to other regions in aggregate. In contrast, PW from Latin America was statistically significantly less likely to contain TC than PW from other geographic regions in aggregate.

It is unclear whether there is a difference in PW quality between urban and rural settings, since so few studies have reported on PW quality in rural areas. Although PW industries are often located in urban regions, supply chains can deliver PW products from urban areas to remote rural settings. The change in safety of PW from urban points of manufacture to rural distribution areas has yet to be examined. Additionally, some small-scale PW producers are located in rural areas. In order to ensure PW products produced and distributed in rural areas meet national standards, it is advised that they be included in monitoring frameworks.

With the exception of one study from Colombia [194], the widespread consumption of sachet water is specific to LICs. Recent studies have reported the growth of the sachet water industry in areas of sub-Saharan Africa [12,16]. This review has shown that small bottled water is significantly less likely to contain FIB and TC compared to all other PW types in general and sachet water products in particular. In most places, bottled water is far more expensive per liter than sachet water [107,143]. The difference in quality between the two PW types may be a result of regulatory agencies focusing on bottled water since it is a more formal industry whereas sachet water is often more informal. Additionally, sachet water is more readily produced in small facilities that can rapidly relocate to avoid regulatory scrutiny or action [12]. Consumers of lower economic status who may not be able to purchase bottled water may therefore incur a greater risk of exposure to microbial contamination if they purchase other PW types. In a study of slum households in Accra, Ghana, sachet consumers tended to be of the poorest socio-economic level [204]. However, in contrast, data from recent Multiple Indicator Cluster Surveys (MICS) have demonstrated that the highest proportions of consumers primarily using sachet water were within the richest quintile in both Ghana and Nigeria [205,206]. Further work is needed to understand these apparently contradictory findings.

There is evidence that the quality of PW decreases along the supply chain [67,75,92,140], although few studies examined this in detail. Of the included studies, 10 examined the microbial quality of products along the supply chain and collected samples from manufacturers and POS. However, only six of these reported the results by sample location (at manufacturer or from POS) (S2 Table). The results of the six studies do not give conclusive evidence for differences in microbial quality with regards to FIB from manufacturers to POS, as none of the studies tracked PW products from the same batch and the results must be interpreted accordingly.

Sachet water presents an additional potential pathway of exposure due to the typical method of consumption in which consumers bite directly into the package. While only three studies examined exterior (packaging) contamination, all reported a proportion of exterior samples were positive for FIB. The exteriors of PW samples from street vendors were more frequently contaminated with TC compared to those of samples from retail stores [83,85,92]. While the impact of exterior contamination on health is unclear, it seems reasonable to recommend that sachets should not be removed from secondary packaging prior to sale in order to minimize exterior contamination.

A pervasive problem faced in data extraction was the inconsistent reporting of results according to brands or samples. Numerous studies reported collecting multiple samples per brand, however, results were then reported by brand rather than individual samples. Thus the results were biased upward, since one positive sample from a brand would be reported as a positive brand. Future research should clearly report all results according to sample and brand, where required.

Few studies compared small bottles to large bottles; however, the results from the meta-regression and qualitative study suggest that large bottles are more frequently contaminated with TC than smaller bottles. In many geographic regions, larger bottles are sold in 18–20 liter reusable containers while smaller bottled water is often sold in single-use containers. The higher prevalence of TC in large bottles may be a result of inadequate cleaning and disinfection of the reusable bottles at the manufacturing or refilling facility [24,122]. Although only a few studies examined larger bottles and dispensers, the review suggests that when bottles are installed on dispensers, additional contamination of both FIB and TC may occur. This could be due to improper maintenance of the dispenser including infrequent or ineffective cleaning [116]; however none of the studies reported a paired analysis of large bottles before and after installation. Consumer education about the proper use and cleaning of dispensers and improved design may help to reduce contamination of bottles.

PW provides a convenient source of water for consumption at home and also in settings outside the home. PW is often sold and consumed at restaurants, outdoor markets, in the streets [75,83], and near schools [114], in addition to mass gatherings such as sporting events or concerts. PW may also be available in workplaces [116,199], health care facilities, and emergency situations. A survey of PW consumers in urban Ibadan, Nigeria reported that 37% used sachet water outside the home [6]. International policymakers have recognized the importance of non-household settings and new water development goals and monitoring frameworks should include these settings [207209]. The number of people exposed to unimproved water sources outside the home is unclear. Thus, PW may provide additional public health benefits as it could provide a safer alternative water source for consumption in non-household settings.

Policy Implications

PW can provide safe water to large populations in diverse and in some cases under-served settings. Therefore, policymakers and regulators should acknowledge PW as an important source of water for consumption. However, current legislation and regulation of PW products and subsequent enforcement are imperfect, and as is the case with other sources of water for consumption, it has the potential to transmit waterborne diseases. Improvements to the legislative and regulatory frameworks surrounding PW products offer an opportunity for governments to capitalize on the potential public health benefits associated with PW.

The establishment of national standards for water quality, hygienic production, packaging, and distribution of PW products would set a minimum level of contamination that is acceptable and outline requirements for PW producers to meet. The CAC provides free standards and guidelines for water quality and hygienic production of bottled water that may be used as a starting point for policymakers interested in establishing national PW regulations. In areas where sachets are prevalent, they should be included in national regulations similar to bottled water and other vended products.

Sachets present distinct challenges to regulators compared to bottled water products. As the production of sachets can be easily performed by laypeople, especially if they are hand-filled, it can be difficult to track and ensure the quality of these products. Hand-filled sachets are typically produced without water treatment and using unhygienic methods with the result that many are frequently contaminated with FIB [146,147,154]. Therefore, in regions where hand-filled sachets are widely used officials should focus on eliminating their production and distribution.

As there is potential for disease transmission through PW, regulators should focus on improving their regulatory and monitoring systems to ensure public safety with regards to PW produced and/or distributed within their borders. The results suggest that monitoring should not only include sampling at the PW manufacturing facility but also at POS. Additional research is needed to examine degradation along the supply chain and elucidate the factors associated with contamination in order to inform effective regulation, control, and/or remediation.

As PW products are often more expensive than other sources per liter, there is an added economic burden on households relying on PW as their primary source of water for consumption. Since poorer households often purchase cheaper PW types (e.g. sachet water) that are often of lower quality, there are equity consequences to under-regulation. A recent study in Ibadan, Nigeria of consumer attitudes towards PW reported that 94% of respondents found the price of sachet water to be affordable [6]. It is unclear if additional regulation would result in PW producers increasing the cost of their products and thus create a barrier for lower income households to purchase PW [16].

As the results have suggested that PW may be a safer water source for consumption in some settings, regulators should seek to simultaneously improve the quality of PW in addition to other water sources used for consumption. The availability of PW does not eliminate the demand for piped water and/or other improved sources, as other domestic activities such as bathing and laundry require a larger volume of water, beyond what would be reasonable for households to obtain from PW. While the quality of water has health implications, there are also health effects related to the quantity of water available for hygiene purposes [210]. Therefore, while PW may be a safer water source for consumption, it cannot be a substitute for sufficient water supplies either at the household or community level.

Limitations

This review included only a limited number of microbial quality parameters, TC, TTC, and E. coli. E. coli and TTC were chosen because they are recommended by the WHO as indicators of microbial drinking water quality, while TC was chosen because its presence in drinking water indicates inadequate disinfection [25]. While this is the first comprehensive review of microbial quality of PW, it does not explore other important indicator bacteria, such as enterococci, Pseudomonas aeruginosa, or other microbial contaminants such as protozoa, viruses, and helminths which are more resilient to many drinking water treatment and disinfection processes, such as chlorination [211]. PW products that are free from coliforms are not necessarily free from pathogens. A review of PW quality with respect to other key microbial indicators such as other bacteria, protozoa, viruses, helminths, and fungi would help provide a fuller picture of the microbial quality and safety of PW products.

Although PW standards may vary between countries, comparison of PW quality results to national guidelines was not within the scope of this review. In order to compare the microbial quality of PW from different countries, we used the guideline of no detectable E. coli in 100mL from the WHO Guidelines for Drinking Water Quality as the standard for comparison [25]. In certain countries, the results of some PW studies may be in compliance with national standards, although they would not meet the WHO guideline.

Natural mineral water is generally considered to be free from pathogenic organisms at the source; however, it does contain natural bacterial flora [212,213]. Regulations for the heterotrophic plate count (HPC) of natural mineral water often only require products to comply within 12 hours of bottling, however, previous research has shown HPC to increase after bottling [123]. Although the presence of HPC has not been associated with gastrointestinal illnesses, high counts can interfere with the detection of coliform bacteria using analytical methods that utilize lactose-based culture media [214]. Studies did not consistently report whether products were classified as natural mineral water, and therefore a comparison between mineral water and non-mineral water was not possible. Accordingly, some reported proportions of positive samples might have been underestimated if membrane filtration was used and high levels of HPC were present.

This review combines studies that used different analytical methods to detect TC and FIB. Differences in results may be due to the methods used, handling and transport of samples, hold times, randomization of sample collection, the use of quality control and quality assurance measures, and study settings. The study quality score used in this review was developed for studies of microbial water quality [31] but may not adequately reflect reliability of water quality assessments in individual studies as it is limited to reported information and equal weights were applied to the criteria. Studies reporting by brand instead of by sample could have overestimated the reported proportion of positive samples, since any one positive sample from one brand would result the brand being reported as positive. Additionally, some studies did not report the size of bottled water products analyzed, or if sachets were machine-filled or hand-filled, thus leading to possible misclassification with regards to PW type.

The search strategy may not have identified all relevant papers. It was designed to capture papers examining bottled and sachet water. However while screening papers, studies referred to larger >5 L bottles using other words such as ‘coolers’, ‘dispensers’ [65,116], or ‘demijohns’ [76], which were not included in the search strategy. In addition, search terms in different translations were not included in the strategy. While some papers examining larger bottled water products were captured through the search strategy, these additional names were not included and thus, this may not be an exhaustive review of large bottled water products.

Papers published in languages other than English, French, Portuguese, Spanish, or Turkish were excluded from this review, which may have introduced bias. During the screening phase, 35 papers published in other languages were identified through title and abstract as potentially relevant to the review, however the full text was not available in one of the five review languages.

Finally, comparison between geographic regions may have been confounded by the availability of studies from different countries (Fig 2), for example 71% of the included studies from Latin America were from Brazil, an upper-middle income country. Studies from Nigeria accounted for almost half (48%) of the studies from Africa.

Conclusions

Consumers of PW products often perceive these products to be of higher quality than other water sources, since they assume that some form of additional water treatment has occurred. In the majority of studies, PW has been shown to be less likely to contain FIB and TC than other sources of water for consumption. As the PW industry continues to grow in LICs, it provides households with an option for safer water at and away from home, especially for those who are otherwise unlikely to gain access to a reliable, safe water supply in the near future.

The presence of FIB in finished PW products in several studies suggests the need for improved manufacturing processes, as well as improved regulation, monitoring, and enforcement. The inclusion of PW products along with other sources used for consumption in international, national, and local water quality monitoring frameworks would help to ensure potential benefits are realized.

This review demonstrates that small bottled water products are less likely to contain FIB and TC contamination than sachet water products, which are often of lower-cost. The convenience and price of sachet water enables many low-income households to obtain drinking water that may be safer than many other alternative sources. However, the disparity in quality between bottled and sachet water raises concerns over the equity of exposure to FIB among PW users. While PW is not a viable long-term solution as it is unable to meet household demand for domestic water quantity, in some contexts it may be the least unsafe source of water for consumption that is available to consumers. Therefore, the simultaneous improvement of the quality of both PW and municipal supplies and the continued expansion of improved water sources are recommended.

Supporting Information

S1 Dataset. Database of extracted data from included studies.

https://doi.org/10.1371/journal.pone.0140899.s001

(XLSX)

S1 Fig. PRISMA Checklist for items to report for a systematic review and meta-analysis.

https://doi.org/10.1371/journal.pone.0140899.s002

(DOC)

S2 Fig. Study quality.

Study quality rating of included studies.

https://doi.org/10.1371/journal.pone.0140899.s003

(DOCX)

S3 Fig. Funnel plot of meta-analysis of PW and other drinking water sources.

Egger’s funnel plot for meta-analysis of FIB contamination of PW and other drinking water sources.

https://doi.org/10.1371/journal.pone.0140899.s004

(DOCX)

S4 Fig. Funnel plot of meta-analysis of PW and tap water sources.

Egger’s funnel plot for meta-analysis of FIB contamination of PW and tap water sources.

https://doi.org/10.1371/journal.pone.0140899.s005

(DOCX)

S1 Table. Results from studies examining the microbial quality of packaged water along the supply chain.

https://doi.org/10.1371/journal.pone.0140899.s006

(DOCX)

S2 Table. Small bottled water analysis.

Meta-regression for small bottled water samples only

https://doi.org/10.1371/journal.pone.0140899.s007

(DOCX)

S3 Table. Results comparing PW types within studies collecting data on more than one PW type.

https://doi.org/10.1371/journal.pone.0140899.s008

(DOCX)

S1 Text. Systematic review protocol.

Detailed description of systematic review protocol.

https://doi.org/10.1371/journal.pone.0140899.s009

(DOCX)

Acknowledgments

We are grateful to Ayse Ecrumen who assisted with full text reviews and data extraction of Turkish papers. We would also like to thank Mellanye Lackey and the staff at the Health Sciences Library at UNC-CH for their assistance with the online searches and obtaining full texts of identified articles.

Author Contributions

Conceived and designed the experiments: ARW RB MBF RC JB. Performed the experiments: ARW RB MBF EK. Analyzed the data: ARW RB. Wrote the paper: ARW RB MBF RC EK JB.

References

  1. 1. Ward LA, Cain OL, Mullally RA, Holliday KS, Wernham AGH, Baillie PD, et al. Health beliefs about bottled water: A qualitative study. BMC Public Health. 2009;9:196. pmid:19545357
  2. 2. Hu Z, Morton LW, Mahler RL. Bottled water: United States consumers and their perceptions of water quality. Int J Environ Res Public Health. 2011;8:565–78. pmid:21556204
  3. 3. Johnstone N, Serret Y. Determinants of bottled and purified water consumption: results based on an OECD survey. Water Policy. 2012;14:668–79.
  4. 4. McLeod L, Bharadwaj L, Waldner C. Risk factors associated with the choice to drink bottled water and tap water in rural Saskatchewan. Int J Environ Res Public Health. 2014;11:1626–46. pmid:24487453
  5. 5. Rodwan JG Jr.. Bottled Water 2011: The Recovery Continues. Bottled Water Report. 2011:12–21.
  6. 6. Opatunji OS, Odhiambo FO. Consumption practices and user perception of an emerging alternative drinking water option (sachet water) in Ibadan, Nigeria. 35th WEDC Int Conf 6–8 July 2011, Loughborough, UK. 2011:1–8.
  7. 7. Thompson J, Porras IT, Tumwine JK, Mujwahuzi MR, Katui-katua M, Johnstone N, et al. Drawers of water II: 30 years of change in domestic water use & environmental health in east Africa. London: International Institute for Environment and Development; 2001.
  8. 8. Bain R, Cronk R, Hossain R, Bonjour S, Onda K, Wright J, et al. Global assessment of exposure to faecal contamination through drinking water based on a systematic review. Trop Med Int Health. 2014;19:917–27. pmid:24811893
  9. 9. Onda K, LoBuglio J, Bartram J. Global access to safe water: accounting for water quality and the resulting impact on MDG progress. Int J Environ Res Public Health. 2012;9:880–94. pmid:22690170
  10. 10. Wright J, Gundry S, Conroy R. Household drinking water in developing countries: a systematic review of microbiological contamination between source and point-of-use. Trop Med Int Heal. 2004;9:106–17.
  11. 11. Shields KF, Bain RE, Cronk R, Wright J a., Bartram J. Association of Supply Type with Fecal Contamination of Source Water and Household Stored Drinking Water in Developing Countries: A Bivariate Meta-analysis. Environ Health Perspect. 2015.
  12. 12. Stoler J, Weeks JR, Fink G. Sachet drinking water in Ghana’s Accra-Tema metropolitan area: Past, present, and future. J Water Sanit Hyg Dev. 2012;2:223–40.
  13. 13. Codex Alimentarius. Codex Standard for Natural Mineral Waters. CODEX STAN 108–1981. Geneva: 1981.
  14. 14. Benneh G, Songsore J, Nabila J, Amuzu A, Tutu K, Yangyuoru Y, et al. Environmental Problems and the Urban Household in the Greater Metropolitan Area (GAMA)—Ghana. Stockholm: Stockholm Environmental Institute; 1993.
  15. 15. Ajayi AA, Sridhar MKC, Adekunle LV, Oluwande PA. Quality of packaged waters sold in Ibadan, Nigeria. Afr J Biomed Res. 2008;11:251–8.
  16. 16. Dada AC. Packaged water: optimizing local processes for sustainable water delivery in developing nations. Global Health. 2011;7:24. pmid:21801391
  17. 17. Abd El-Salam MMM, El-Ghitany EMA, Kassem MMM. Quality of bottled water brands in Egypt Part II: Biological water examination. J Egypt Public Health Assoc. 2008;83:468–86. pmid:19493513
  18. 18. Ackah M, Anim AK, Gyamfi ET, Acquah J, Nyarko ES, Kpattah L. Assessment of the quality of sachet water consumed in urban townships of Ghana using physico-chemical indicators : A preliminary study. Adv Appl Sci Res. 2012;3:2120–7.
  19. 19. Addo KK, Mensah GI, Bekoe M, Bonsu C, Akyeh ML. Bacteriological quality of sachet water produced and sold in Teshie-Nungua suburbs of Accra, Ghana. Afr J Food Agric Nutr Dev. 2009;9:1019–30.
  20. 20. Kwakye-Nuako G, Borketey PB, Mensah-Attipoe I, Asmah RH, Ayeh-Kumi PF. Sachet drinking water in accra: the potential threats of transmission of enteric pathogenic protozoan organisms. Ghana Med J. 2007;41:62–7. pmid:17925844
  21. 21. Obiri-Danso K, Okore-Hanson A, Jones K. The microbiological quality of drinking water sold on the streets in Kumasi, Ghana. Lett Appl Microbiol. 2003;37:334–9. pmid:12969499
  22. 22. Svagzdiene R, Lau R, Page RA. Microbiological quality of bottled water brands sold in retail outlets in New Zealand. Water Sci Technol Water Supply. 2010;10:689–99.
  23. 23. Vantarakis A, Smaili M, Detorakis I, Vantarakis G, Papapetropoulou M. Diachronic long-term surveillance of bacteriological quality of bottled water in Greece (1995–2010). Food Control. 2013;33:63–7.
  24. 24. Falcone-Dias MF, Emerick GL, Farache-Filho A. Mineral water: A microbiological approach. Water Sci Technol Water Supply. 2012;12:556–62.
  25. 25. World Health Organization. Guidelines for drinking-water quality, 4th ed. vol. 38. 2011.
  26. 26. U.S. EPA. Causes of Total Coliform-Positive Occurrences in Distribution Systems. Washington, DC: U.S. Environmental Protection Agency; 2006.
  27. 27. Codex Alimentarius. General Standard for Bottled/Packaged Drinking Waters (Other than Natural Mineral Waters) CODEX STAN 227–2001. Geneva: 2001.
  28. 28. International Bottled Water Association. Bottled Water Code of Practice 2012;22314. http://www.bottledwater.org/files/IBWA-CODE-OF-PRACTICE-2012-FINAL.pdf (accessed June 26, 2013).
  29. 29. Prüss-Ustün A, Bartram J, Clasen T, Colford JM, Cumming O, Curtis V, et al. Burden of disease from inadequate water, sanitation and hygiene in low- and middle-income settings: A retrospective analysis of data from 145 countries. Trop Med Int Health. 2014;19:894–905. pmid:24779548
  30. 30. Moher D, Liberati A, Tetzlaff J, Altman DG. Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. PLoS Med. 2009;6:e1000097. pmid:19621072
  31. 31. Bain R, Cronk R, Wright J, Yang H, Slaymaker T, Bartram J. Fecal contamination of drinking-water in low- and middle-income countries: a systematic review and meta-analysis. PLoS Med. 2014;11:e1001644. pmid:24800926
  32. 32. Warton DI, Hui FKC. The arcsinine: The analysis of proportions in ecology. Ecology. 2011;92:3–10. pmid:21560670
  33. 33. United Nations. Millennium Development Indicators: World and regional groupings 2003. http://mdgs.un.org/unsd/mdg/Host.aspx?Content=Data/RegionalGroupings (accessed February 18, 2014).
  34. 34. World Bank. Country and Lending Groups 2014. http://data.worldbank.org/about/country-classifications/country-and-lending-groups (accessed February 18, 2014).
  35. 35. Sweeting MJ, Sutton AJ, Lambert PC. What to add to nothing? Use and avoidance of continuity corrections in meta-analysis of sparse data. Stat Med. 2004;23:1351–75. pmid:15116347
  36. 36. Higgins JPT, Thompson SG. Quantifying heterogeneity in a meta-analysis. Stat Med. 2002;21:1539–58. pmid:12111919
  37. 37. Egger M, Smith GD, Altman DG. Systematic reviews in health care: Meta-analysis in context. 2nd ed. London: BMJ Books; 2001.
  38. 38. Adekunle L V, Mkc S, Ajayi a a, Oluwade P a, Olawuyi JF. an Assesment of the Health and Social Economic Implications of Satchet Water N Ibadan Nigeria: a Public Health Challenge. African J Biomed Res. 2004;7:5–8.
  39. 39. El-Fadel M, Maroun R, Quba’A R, Mawla D, Sayess R, Massoud M a., et al. Determinants of diarrhea prevalence in urban slums: A comparative assessment towards enhanced environmental management. Environ Monit Assess. 2014;186:665–77. pmid:24078142
  40. 40. Venieri D, Vantarakis a., Komninou G, Papapetropoulou M. Microbiological evaluation of bottled non-carbonated (“still”) water from domestic brands in Greece. Int J Food Microbiol. 2006;107:68–72. pmid:16271413
  41. 41. Abayasekara CL, Herath WHMAT, Adikaram NKB, Chandrajith R, Illapperuma SC, Sirisena AS, et al. Microbiological quality of bottled water in Sri Lanka: A preliminary survey. Proc Perad Univ Res Sess Sri Lanka. 2007;12:49–50.
  42. 42. Abo-Amer AE, Soltan E-SM, Abu-Gharbia MA. Molecular approach and bacterial quality of drinking water of urban and rural communities in Egypt. Acta Microbiol Immunol Hung. 2008;55:311–26. pmid:18800596
  43. 43. Addo KK, Mensah GI, Donkor B, Bonsu C, Akyeh ML. Bacteriological quality of bottled water sold on the Ghanian market. African J Food Agric Nutr Dev. 2009;9:1378–87.
  44. 44. Adegoke OA, Bamigbowu EO, Oni ES, Ugbaja KN. Microbiological examination of sachet water sold in Aba, Abia- State, Nigeria. Glob Res J Microbiol. 2012;2:62–6.
  45. 45. Adesiji AR. Microbiological quality of packaged drinking water brands marketed in Minna metropolis, North Central Nigeria. Niger J Technol Res. 2012;7:15–8.
  46. 46. Afiukwa NF, Romanus II, Azubuike AC, Eze AT, Collins ON, Chidiebube NA. Presence of antibiotic resistant coliforms in sachet water sold in some parts of South Eastern Nigeria. J Microbiol Antimicrob. 2010;2:51–4.
  47. 47. Ahimah JK, Ofosu SA. Evaluation of the quality of sachet water vended in the New Juaben municipality of Ghana. Int J Water Resour Environ Eng. 2012;4:134–8.
  48. 48. Ahmad M, Bajahlan AS. Quality comparison of tap water vs. bottled water in the industrial city of Yanbu (Saudi Arabia). Environ Monit Assess. 2009;159:1–14. pmid:19011982
  49. 49. Ahmed W, Yusuf R, Hasan I, Ashraf W, Goonetilleke A, Toze S, et al. Fecal indicators and bacterial pathogens in bottled water from Dhaka, Bangladesh. Brazilian J Microbiol. 2013;44:97–103.
  50. 50. Akinde SB, Nwachukwu MI, Ogamba AS. Storage effects on the quality of sachet water produced within Port Harcourt Metropolis, Nigeria. Jordan J Biol Sci. 2011;4:157–64.
  51. 51. Akpoborie IA, Ehwarimo A. Quality of packaged drinking water produced in Warri Metropolis and potential implications for public health. J Environ Chem Ecotoxicol. 2012;4:195–202.
  52. 52. Alabdula’aly AI, Khan MA. Microbiological quality of bottled water in Saudi Arabia. J Environ Sci Heal Part A Environ Sci Eng Toxicol. 1995;30:2229–41.
  53. 53. Allanana JA, Tokdung M, Badung BP, Banwat EB, Egah DZ. Bacteriological suitability of packaged pure water. J Med Trop. 2003;5:53–7.
  54. 54. AlOtaibi ELS. Bacteriological assessment of urban water sources in Khamis Mushait Governorate, southwestern Saudi Arabia. Int J Heal Geogr. 2009;8:16.
  55. 55. Alves NC, Odorizzi AC, Goulart FC. Análise microbiológica de águas minerais e de água potável de abastecimento, Marília, SP. Rev Saúde Pública. 2002;36:749–51.
  56. 56. Ampofo JA, Andoh A, Tetteh W, Bello M. Microbiological quality and health risks of packaged water produced in southern Ghana. J Appl Sci Technol. 2008;12:88–97.
  57. 57. Andueza F. Calidad bacteriológica del agua mineral envasada expendida en la ciudad de Mérida: Estudio transversal julio-agosto año 1998. Rev La Fac Farm. 2000;38:9–19.
  58. 58. Ante VO, Shehu AU, Musa KY. Microbial and chemical portability of packaged drinking water sold in Kaduna, Nigeria. Eur J Sci Res. 2005;18:201–9.
  59. 59. Anunobi CC, Onajole AT, Ogunnowo BE. Assessment of the quality of packaged water on sale in Onitsha Metropolis. Nig Ot J Hop Med. 2006;16:56–9.
  60. 60. Anuonye JC, Maxwell OM, Caleb MY. Quality of sachet water produced and marketed in Minna metropolis, North Central Nigeria. Afr J Food Sci. 2012;6:583–8.
  61. 61. Anyanwu CU. Studies on Antibiotic Resistance of Some Bacterial Isolates from Sachet Water Samples in Nsukka, Nigeria. Bio-Research. 2009;7:509–13.
  62. 62. Arruda M das GP, Mourão ÂF de LD, de Carvalho MLM, de Arruda HB. Águas minerais produzidas no estado do ceará nos anos 2004/2005—Avaliação dos riscos e busca por soluções. Hig Aliment. 2008;22:56–9.
  63. 63. Asamoah DN, Amorin R. Assessment of the quality of bottled/sachet water in the Tarkwa-Nsuaem municipality (TM) of Ghana. Res J Appl Sci Eng Tech. 2011;3:377–85.
  64. 64. Basma SH. Complementary water sources in a selected urban area in Beirut, Lebanon: Public perceptions, regulations and quality. American University of Beirut, 2004.
  65. 65. Baumgartner A, Grand M. Bacteriological quality of drinking water from dispensers and possible control measures. Food Prot. 2006;69:3043–6.
  66. 66. Bharath J, Mosodeen M, Motilal S, Sandy S, Sharma S, Tessaro T, et al. Microbial quality of domestic and imported brands of bottled water in Trinidad. Int J Food Microbiol. 2003;81:53–62. pmid:12423918
  67. 67. Biadglegne F, Tessema B, Kibret M, Abera B, Huruy K, Anagaw B, et al. Physicochemical and bacteriological quality of bottled drinking water in three sites of Amhara Regional State, Ethiopia. Ethiop Med J. 2009;47:277–84. pmid:20067142
  68. 68. Brandão MLL, Rosas C de O, Medeiros V de M, Warnken MB, Bricio SML, da Silva AML, et al. Comparação das técnicas do número mais provável (NMP) e de filtração em membrana na avaliação da qualidade microbiológica de água mineral natural. Rev Inst Adolfo Lutz. 2012;71:32–9.
  69. 69. Cabral D, Fernández PVE. Fungal spoilage of bottled mineral water. Int J Food Microbiol. 2002;72:73–6. pmid:11843415
  70. 70. Castillo PM, Torner MJ, Pla S, García L. Control sanitario de aguas minerales naturales envasadas. Alimentaria. 1995;33:105–9.
  71. 71. Chesca AC, Santos ALS, D’Angelis CEM. Análise microbiológica de águas minerais. Hig Aliment. 2011;25:176–9.
  72. 72. Coelho DA, Silva PM de F e, Veiga SMOM, Fiorini JE. Avaliação da qualidade microbiológica de águas minerais comercializadas em supermercados da cidade de Alfenas, MG. Hig Aliment. 2007;21:88–92.
  73. 73. Da Silva JL, Calazans GMT. Avaliação bacteriológica de águas consumidas na cidade do Recife-PE. Forum Deans Ext. Brazilian Public Univ., Paraíba, Brazil: 2002, p. 1–10.
  74. 74. Da Silva MEZ, Santana RG, Guilhermetti M, Filho IC, Endo EH, Ueda-Nakamura T, et al. Comparison of the bacteriological quality of tap water and bottled mineral water. Int J Hyg Environ Health. 2008;211:504–9. pmid:18206422
  75. 75. Dada AC. Sachet water phenomenon in Nigeria: Assessment of the potential health impacts. Afr J Microbiol Res. 2009;3:15–21.
  76. 76. Dalman Ö, Kutanis VV, Col M. Microbiological quality of different bottled water brands, marketed in Trabzon, Turkey. Asian J Chem. 2013;25:1879–83.
  77. 77. Danso-Boateng E, Frimpong IK. Quality analysis of plastic sachet and bottled water brands produced or sold in Kumasi, Ghana. Int J Dev Sustain. 2013;2:2222–32.
  78. 78. Demirci AŞ, Gümüş T, Demirci M. Damacana Suların Mikrobiyolojik Kalitesi Üzerine Pompa Temizliğinin Etkisi. Tekirdağ Ziraat Fakültesi Derg. 2007;4:271–5.
  79. 79. Dias MFF, Farache Filho A. Qualidade microbiológica de águas minerais em embalagens individuais comercializadas em Araraquara, SP. Alim Nutr. 2007;18:177–81.
  80. 80. Dodoo DK, Quagraine EK, Okai-Sam F, Kambo DJ, Headley J V. Quality of “sachet” waters in the Cape Coast municipality of Ghana. J Env Sci Heal A Tox Hazard Subst Env Eng. 2006;41:329–42.
  81. 81. Echave IM, Bermejo DG, Guillén JJI. Análisis microbiológico de aguas de bebida envasadas comercializadas en la ciudad de Sevilla. Alimentaria. 1994;257:39–42.
  82. 82. Edberg SC, Gallo P, Kontnick C. Analysis of the virulence characteristics of bacteria isolated from bottled, water cooler, and tap water. Microb Ecol Heal Dis. 1996;9:67–77.
  83. 83. Egwari LO, Iwuanyanwu S, Ojelabi CI, Uzochukwu O, Efiok WW. Bacteriology of sachet water sold in Lago, Nigeria. East Afr Med J. 2005;82:235–40. pmid:16119752
  84. 84. Ehlers MM, van Zyl WB, Pavlov DN, Müller EE. Random survey of the microbial quality of bottled water in South Africa. Water SA. 2004;30:203–10.
  85. 85. Ejechi EO, Ejechi BO. Safe drinking water and satisfaction with environmental quality of life in some oil and gas industry impacted cities of Nigeria. Soc Indic Res. 2008;85:211–22.
  86. 86. El-Abagy MM, Dutka BJ, Kamel M, el Zanfaly HT. Incidence of coliphage in potable water supplies. Appl Environ Microbiol. 1988;54:1632–3. pmid:3415229
  87. 87. Ezeugwunne IP, Agbakoba NR, Nnamah NK, Anahalu IC. The prevalence of bacteria in packaged sachets water sold in Nnewi, South East, Nigeria. World J Dairy Food Sci. 2009;4:19–21.
  88. 88. Falcone-Dias MF, Farache Filho A. Quantitative variations in heterotrophic plate count and in the presence of indicator microorganisms in bottled mineral water. Food Control. 2013;31:90–6.
  89. 89. Farache Filho A, Dias MFF. Qualidade microbiológica de águas minerais em galões de 20 litros. Alim Nutr. 2008;19:243–8.
  90. 90. Farache Filho A, Dias MFF, Taromaru PH, Cerqueira CS, Duque JG. Qualidade microbiológica de águas minerais não carbonatadas em embalagens de 1,5 litros, comercializadas em Araraquara-SP. Alim Nutr. 2008;19:421–5.
  91. 91. Fewtrell L, Kay D, Wyer M, Godfree A, O’Neill G. Microbioloigcal quality of bottled water. Water Sci Technol. 1997;35:47–53.
  92. 92. Fisher M, Williams A, Jalloh M, Saquee G, Bain R, Bartram J. Microbiological and chemical quality of packaged water and stored household water for consumption in Freetown, Sierra Leone n.d.
  93. 93. Franco RMB, Cantusio Neto R. Occurrence of cryptosporidial oocysts and giardia cysts in bottled mineral water commercialized in the city of Campinas, State of São Paulo, Brazil. Mem Inst Oswaldo Cruz. 2002;97:205–7. pmid:12016445
  94. 94. Frischknecht DS, Santana AP. Determinação do número mais provável de coliformes, em águas minerais comercializadas no distrito federal. Hig Aliment. 2008;22:102–6.
  95. 95. Fuzihara TO, Pisani B, Simões M, Brigído BM, Leopoldo C, Vannucci L, et al. The occurence of Aeromonas spp in drinking water. Rev Inst Adolfo Lutz. 2005;64:122–7.
  96. 96. Gangil R, Tripathi R, Patyal A, Dutta P, Mathur K. Bacteriological evaluation of packaged bottled water sold at Jaipur city and its public health significance. Vet World. 2013;5:27–30.
  97. 97. Geldreich EE, Nash HD, Reasoner DJ, Taylor RH. The necessity of controlling bacterial populations in potable waters- Bottled water and Emergency Supplies. J Am Water Work Assoc. 1975;67:117–24.
  98. 98. Gönül ŞA, Karapinar M. The microbiological quality of drinking water supplies of Izmir City: The incidence of Yersinia enterocolitica. Int J Food Microbiol. 1991;13:69–73. pmid:1863530
  99. 99. Grant MA. Analysis of Bottled Water for Escherichia coli and Total Coliforms. J Food Prot. 1998;61:334–8. pmid:9708306
  100. 100. Guimarães APRC, Serafini ÁB. Avaliação da qualidade microbiológica de amostras de água mineral natural, envasada, comercializadas em Goiânia, Goiás. Congr Pesqui. 2005;54.
  101. 101. Herath AT, Abayasekara CL, Chandrajith R, Adikaram NKB. Temporal variation of microbiological and chemical quality of noncarbonated bottled drinking water sold in Sri Lanka. J Food Sci. 2012;77:M160–4. pmid:22384963
  102. 102. Holt S. A Survey of water storage practices and beliefs in households in Bonao, Dominican Republic in 2005. University of Georgia State University, 2009.
  103. 103. Hunter PR, Burge SH. The bacteriological quality of bottled natural mineral waters. Epidemiol Infect. 1987;99:439–43. pmid:3678404
  104. 104. Islam S, Begum HA, Nili NY. Bacteriological safety assessment of municipal tap water and quality of bottle water in Dhaka City: Health hazard analysis. Bangladesh J Med Microbiol. 2010;04:9–13.
  105. 105. Ismail AH, Zowain A, Sufar E. Quality assessment of various local bottled waters in different Iraqi markets. Eng Tech J. 2013;31:660–77.
  106. 106. Jeena MI, Deepa P, Mujeeb Rahiman KM, Shanthi RT, Hatha AAM. Risk assessment of heterotrophic bacteria from bottled drinking water sold in Indian markets. Int J Hyg Env Heal. 2006;209:191–6.
  107. 107. Kassenga GR. The health-related microbiological quality of bottled drinking water sold in Dar es Salaam, Tanzania. J Water Health. 2007;5:179–89. pmid:17402289
  108. 108. Khan MR, Saha ML, Kibria AHMG. A bacteriological profile of bottled water sold in Bangladesh. World J Microbiol Biotechnol. 1992;8:544–5. pmid:24425576
  109. 109. Khaniki GRJ, Zarei A, Kamkar A, Fazlzadehdavil M, Ghaderpoori M, Zarei A. Bacteriological Evaluation of Bottled Water from Domestic Brands in Tehran markets, Iran. World Appl Sci J. 2010;8:274–8.
  110. 110. Khatoon A, Pirzada ZA. Bacteriological quality of bottled water brands in Karachi, Pakistan. Biologia (Bratisl). 2010;56:137–43.
  111. 111. Kokkinakis EN, Fragkiadakis G a., Kokkinaki AN. Monitoring microbiological quality of bottled water as suggested by HACCP methodology. Food Control. 2008;19:957–61.
  112. 112. Korfali SI, Jurdi M. Provision of safe domestic water for the promotion and protection of public health: A case study of the city of Beirut, Lebanon. Environ Geochem Health. 2009;31:283–95. pmid:18958397
  113. 113. Korzeniewska E, Filipkowska Z, Domeradzka S, Włodkowski K. Microbiological quality of carbonated and non-carbonated mineral water stored at different temperatures. Pol J Microbiol. 2005;54 Suppl:27–33. pmid:16457377
  114. 114. Kouadio LP, Ekra NB, Atindehou E, Nanou C, Monnet D. Etude de la potabilité des eaux de boisson en sachet vendues aux abords des écoles primaires publiques d’Abidjan. Bull Soc Pathol Exot. 1998;91:167–8. pmid:9642476
  115. 115. Lal M, Kaur H. A microbiological study of bottled mineral water marketed in Ludhiana. Indian J Public Health. 2006;50:31–2. pmid:17193757
  116. 116. Lévesque B, Simard P, Gauvin D, Gingras S, Dewailly E, Letarte R. Comparison of the microbiological quality of water coolers and that of municipal water systems. Appl Env Microbiol. 1994;60:1174–8.
  117. 117. Mahmood SN, Siddiqui IU, Sultana L, Khan FA. Evaluation of chemical and bacteriological quality of locally produced bottled water. Jour Chem Soc Pak. 2004;26:185–90.
  118. 118. Maimuna W. Assessment of the microbial quality of sachet water in Damaturu-Yobe State, Nigeria. J Asian Sci Res. 2012;2:76–80.
  119. 119. Majumder AK, Islam KMN, Nite NR, Noor R. Evaluation of Microbiological Quality of Commercially Available Bottled Water in the City of Dhaka, Bangladesh. Stanford J Microbiol. 2011;1:24–30.
  120. 120. Mannapperuma WMGCK, Abayasekara CL, Herath GBB, Werellagama DRIB. Potentially pathogenic bacteria isolated from different tropical waters in Sri Lanka. Water Sci Technol Water Supply. 2013;13:1463–9.
  121. 121. Mardani M, Gachkar L, Peerayeh SN, Asgari A, Hajikhani B, Amiri R. Surveying common bacterial contamination in bottled mineral water in Iran. Iran J Clin Infect Dis. 2007;2:13–5.
  122. 122. Marzano MA, Balzaretti CM. Protecting child health by preventing school-related foodborne illnesses: Microbiological risk assessment of hygiene practices, drinking water and ready-to-eat foods in Italian kindergartens and schools. Food Control. 2013;34:560–7.
  123. 123. Massa S, Fanelli M, Brienza MT, Sinigaglia M. The bacterial flora in bottled natural mineral water sold in Italy. J Food Qual. 1997;21:175–85.
  124. 124. Massoud MA, Maroun R, Abdelnabi H, Jamali II, El-Fadel M. Public perception and economic implications of bottled water consumption in underprivileged urban areas. Environ Monit Assess. 2013;185:3093–102. pmid:22828978
  125. 125. Mavridou A, Papapetropoulou M, Boufa P, Lambiri M, Papadakls JA. Microbiological quality of bottled water in Greece. Lett Appl Microbiol. 1994;19:213–6.
  126. 126. Mbaeyi-Nwaoha IE, Egbuche NI. Microbiological evaluation of sachet water and street-vended yoghurt and “Zobo” drinks sold in Nsukka metropolis. Int J Biol Chem Sci. 2012;6:1703–17.
  127. 127. Miranzadeh M, Ehsanifar M, Iranshahi L. Evaluation of bacterial quality and trace elements concentrations in 25 brands of Iranian bottled drinking water. Am Eurasian J Agri Env Sci. 2011;11:341–5.
  128. 128. Moazeni M, Atefi M, Ebrahimi A, Razmjoo P, Vahid Dastjerdi M. Evaluation of chemical and microbiological quality in 21 brands of Iranian bottled drinking waters in 2012: A comparison study on label and real contents. J Environ Public Health. 2013;2013.
  129. 129. Momtaz H, Dehkordi FS, Rahimi E, Asgarifar A. Detection of Escherichia coli, Salmonella species, and Vibrio cholerae in tap water and bottled drinking water in Isfahan, Iran. BMC Public Health. 2013;13:556–62. pmid:23742181
  130. 130. Moshtaghi H, Boniadian M. Microbial quality of drinking water in Shahrekord (Iran). Res J Microbiol. 2007;2:299–302.
  131. 131. Nascimento AR, Azevedo TKL, Filho NEM, Rojas MOAI. Qualidade microbiológica das águas minerais consumidas na cidade de São Luís—MA. Hig Aliment. 2000;14:69–72.
  132. 132. Ndamitso MM, Idris S, Likita MB, Tijani JO, Ajai AI, Bala AA. Physico-chemical and Escherichia coli assessment of selected sachet water produced in some areas of Minna, Niger State, Nigeria. Int J Water Resour Environ Eng. 2013;5:134–40.
  133. 133. Ngozi A., Romanus II, Azubuike AC, Eze T, Egwu OA, Collins ON. Presence of coliform producing extended spectrum beta lactamase in sachet-water manufactured and sold in Abakaliki, Ebonyi State, Nigeria. Int Res J Microbiol. 2010;1:32–6.
  134. 134. Nounou HA, Ali SM, Shalaby MA, Asala RG. The threats of microbial contamination and total dissolved solids in drinking water of Riyadh’s rural areas, Saudi Arabia. Asian Biomed. 2013;7:491–8.
  135. 135. Nunes SM, Fuzihara TO. Avaliação microbiológica das águas minerais envasadas e comercializadas na região do ABC, SP. Hig Aliment. 2011;25:195–9.
  136. 136. Nunes Filho SAP, San’tana AS, Cruz AG. Commercialization conditions and practices influence microbiological quality of mineral waters. J Food Prot. 2008;71:1253–7. pmid:18592755
  137. 137. Nwosu JN, Ogueke CC. Evaluation of sachet water samples in Owerri metropolis. Niger Food J. 2004;22:164–70.
  138. 138. Ogan MT. Microbiological quality of bottled water sold in retail outlets in Nigeria. J Appl Bacteriol. 1992;73:175–81. pmid:1399910
  139. 139. Ogunlesi M, Okiei W, Adjogri SJ, Oshinnuga OM. Physico-chemical and microbial studies on sachet water consumed in Lagos Metropolis, Nigeria. Niger J Heal Biomed Sci. 2009;8:53–7.
  140. 140. Ohanu ME, Udoh IP, Eleazar CI. Microbiological analysis of sachet and tap water in Enugu State of Nigeria. Adv Microbiol. 2012;2:547–51.
  141. 141. Okagbue RN, Dlamini NR, Siwela M, Mpofu F. Microbiological quality of water processed and bottled in Zimbabwe. Afr J Health Sci. 2002;9:99–103. pmid:17298150
  142. 142. Okanlawon OOO, Olayeni F. Quality of sealed polythene water in Kaduna and Lagos. 29th WEDC Int. Conf., Abuja, Nigeria: 2003.
  143. 143. Okioga T. Water quality and business aspects of sachet-vended water in Tamale, Ghana. University of Nairobi, 2007.
  144. 144. Olajubu FA, Mope DA. Bacteriological assessment of “pure water” samples in Ogun State of Nigeria. Niger J Heal Biomed Sci. 2007;6:45–8.
  145. 145. Olaoye OA, Onilude AA. Assessment of microbiological quality of sachet-packaged drinking water in Western Nigeria and its public health significance. Public Health. 2009;123:729–34. pmid:19880150
  146. 146. Olayemi AB. Microbial potability of bottled and packaged drinking waters hawked in Ilorin metropolis. Int J Environ Health Res. 1999;9:245–8.
  147. 147. Oloke JK. Microbiological analysis of hawked water. African J Sci. 1997;1:22–8.
  148. 148. Oluwafemi F, Oluwole ME. Microbiological examination of sachet water due to a cholera outbreak in Ibadan, Nigeria. Open J Med Microbiol. 2012;2:115–20.
  149. 149. Onifade AK, Ilori RM. Microbiological analysis of sachet water vended in Ondo State, Nigeria. Environ Res J. 2008;2:107–10.
  150. 150. Onweluzo JC, Akuagbazie CA. Assessment of the quality of bottled and sachet water sold in Nsukka Town. J Trop Agric Food, Environ Ext. 2010;9:104–10.
  151. 151. Otterholt E, Charnock C. Microbial quality and nutritional aspects of Norwegian brand waters. Int J Food Microbiol. 2011;144:455–63. pmid:21095035
  152. 152. Oyedeji O, Olutiola PO, Moninuola MA. Microbiological quality of packaged drinking water brands marketed in Ibadan metropolis and Ile-Ife city in South Western Nigeria. Afr J Microbiol Res. 2010;4:96–102.
  153. 153. Oyeku OM, Omowumi OJ, Kupoluyi CF, Toye EO. Wholesomeness studies of water produced and sold in plastic sachets (pure water) in Lagos Metropolis. Niger Food J. 2001;19:63–9.
  154. 154. Oyelude EO, Ahenkorah S. Quality of sachet water and bottled water in Bolgatanga municipality of Ghana. Res J Appl Sci Eng Technol. 2012;4:1094–8.
  155. 155. Papapetropoulou M, Tsintzou A, Vantarakis A. Environmental mycobacteria in bottled table waters in Greece. Can J Microbiol. 1997;43:499–502. pmid:9165705
  156. 156. Penland RL, Wilhelmus KR. Microbiologic analysis of bottled water: is it safe for use with contact lenses? Ophthalmology. 1999;106:1500–3. pmid:10442894
  157. 157. Poeta PT, Salomão RG, Veiga SMOM. Avaliação microbiológica de águas minerais envasadas comercializadas no município de Alfenas, M.G. Hig Aliment. 2008;22:32–5.
  158. 158. Pontara AV, Dezuani C, Barbosa AH, dos Santos RA, Pires RH, Martins CHG. Microbiological monitoring of mineral water commercialized in Brazil. Brazilian J Microbiol. 2011;42:554–9.
  159. 159. Rabee AM, Emran FK, Hassoon HA, Al-Dhamin AS. Evaluation of the physco-chemical properties and microbiological content of some brands of bottled water in Baghdad, Iraq. Adv Biores. 2012;3:109–15.
  160. 160. Radhakrishna M, Haseena M, Nisha KV, Maliya P. Bacteriological study of bottled drinking water marketed in Mangalore. J Communi Dis. 2003;35:123–8.
  161. 161. Raji MIO, Ibrahim YKE, Ehinmidu JO. Bacteriological quality of public water sources in Shuni, Tambuwal and Sokoto towns in North-Western Nigeria. J Pharm Bioresour. 2010;7:55–64.
  162. 162. Reddy PS, Ata-ur-Rasheed MD, Sharma S. Microbiological analysis of bottled water. Indian J Med Microbiol. 2000;18:72–6.
  163. 163. Reis JAD, Hoffman P, Hoffman FL. Ocorrência de bactérias aeróbias mesófilas, coliformes totais, fecais e Escherichia Coli, em amostras de águas minerais envasadas, comercializadas no município de São José do Rio Preto, SP. Hig Aliment. 2006;20:109–16.
  164. 164. Resende A, do Prado CN. Perfil microbiológico da água mineral comercializada no distrito federal. SaBios Rev Saúde E Biol. 2008;3:16–22.
  165. 165. Reyes MI, Perez CM, Negron EL. Microbiological assessment of house and imported bottled water by comparison of bacterial endotoxin concentration, heterotrophic plate count, and fecal coliform count. P R Heal Sci J. 2008;27:21–6.
  166. 166. Richards J, Stokely D, Hipgrave P. Quality of drinking water. BMJ. 1992;304:571.
  167. 167. Ritter AC, Tondo EC. Avalição microbiológica de água mineral natural e de tampas plásticas utilizadas em uma indústria da grande porto alegre/RS. Alim Nutr. 2009;20:201–6.
  168. 168. Robles E, Ramírez P, González E, Sáinz G, Martínez B, Durán A, et al. Bottled-water quality in metropolitan Mexico City. Water Air Soil Pollut. 1999;113:217–26.
  169. 169. Rodríguez I, Hardisson A, Burgos A, Rubio C. El autocontrol y el sistema de aricpc en una industria envasadora de agua. Alimentaria. 1999;302:29–32.
  170. 170. Rojas T, Montoya A, Moreno A, Mujica R, Vásquez Y. Formación de biopelículas y susceptibilidad antimicrobiana entre coliformes aislados en agua potable embotellada en Carabobo, Venezuela. Bol Malariol Y Salud Ambient. 2012;52:87–97.
  171. 171. Rosa SP, Pavan da Silva SR, Mann MB, Corção G. Avaliação presença de colifromes totais e fecais em amostras de águas mineral comercializadas em Porto Alegre, RS. Hig Aliment. 2008;22:94–9.
  172. 172. Sabioni JG, Silva IT. Qulidade microbiológica de águas minerais comercializadas em Ouro Preto, MG. Hig Aliment. 2006;20:72–8.
  173. 173. Sant’ana ADS, Silva SCFL, Farani IOJ, Amaral CHR, Macedo VF. Qualidade microbiológica de águas minerais. Ciênc Tecnol Aliment. 2003;23:190–4.
  174. 174. Sasikaran S, Sritharan K, Balakumar S, Arasaratnam V. Physical, chemical and microbial analysis of bottled drinking water. Ceylon Med J. 2012;57:111–6. pmid:23086026
  175. 175. Scarpino PV, Kellner GR, Cook HC. The bacterial quality of bottled vater. J Environ Sci Heal Part A Environ Sci Eng. 1987;22:357–67.
  176. 176. Scoaris DDO, Bizerra FC, Yamada-Ogatta SF, Abreu Filho BAD, Ueda-Nakamura T, Nakamura CV. The occurrence of Aeromonas spp. in the bottled mineral water, well water and tap water from the municipal supplies. Braz Arch Biol Technol. 2008;51:1049–55.
  177. 177. Šefcová H. The effects of storage time on the growth of bacterial flora in bottled drinking water. Cent Eur J Public Heal. 1997;5:32–4.
  178. 178. Sekla LH. Are the alternatives to municipal water truly safer? Can Med Assoc J. 1991;144:1273–5.
  179. 179. Semerjian LA. Quality assessment of various bottled waters marketed in Lebanon. Environ Monit Assess. 2011;172:275–85. pmid:20148363
  180. 180. Sharmin S, Kabir SML, Rahman MM. Qualitative and bacteriological assessment of commercially available bottled water in the city of Mymensingh, Bangladesh. Microbes Heal. 2013;1:81–5.
  181. 181. Shekhar C, Joshi N, Singh A. Physicochemical and microbiological analysis of drinking water. J Vet Public Heal. 2011;9:123–6.
  182. 182. Slade PJ, Falah MA, Al-Ghady AMR. Isolation of Aeromonas hydrophila from bottled waters and domestic water supplies in Saudi Arabia. J Food Prot. 1986;49:471–6.
  183. 183. Souza Coelho MI, Mendes ES, Cruz MCS, Bezerra SS, Silva RPP. Avalição da qulidade microbiológica de águas minerais consumidas na região metropolitana de Recife, Estado de Pernambuco. Maringá. 2010;32:1–8.
  184. 184. Stoler J, Tutu RA, Ahmed H, Frimpong LA, Bello M. Sachet water quality and brand reputation in two low-income urban communities in greater Accra, Ghana. Am J Trop Med Hyg. 2014;90:272–8. pmid:24379244
  185. 185. Sumathy S, Gowrisankar R, Ramesh S. Bacteriological evaluation of marketed mineral water. In: Kumar A, Tripathi G, editors. Water Pollution- Assess. Mangement, Delhi: Daya Publishing House; 2004, p. 224–7.
  186. 186. Tagoe DNA, Nyarko H, Arthur SA, Birikorang E. A study of antibiotic suspectibility pattern of bacteria isolates in sachet drinking water sold in the Cape Coast Metropolis of Ghana. Res J Microbiol. 2011;6:153–8.
  187. 187. Taiwo AM, Gbadebo AM, Awomeso JA. Potability assessment of selected brands of bottled water in Abeokuta, Nigeria. J Appl Sci Environ Mange. 2010;14:47–52.
  188. 188. Tancredi RCP, Cerqueira E, Marins BR. Águas minerais consumidas na cidade do Rio de Janeiro: avaliação da qualidade sanitária. Bol Divulg Técnica E Cient. 2002;4:1–14.
  189. 189. Thurman RB, Athanasopoulos AA, Allan MS, Atchia SM. Bottle wars: England versus Scotland versus France. Int J Food Sci Nutr. 2002;53:209–16. pmid:11951584
  190. 190. Timilshina M, Dahal I, Thapa B. Microbial assessment of bottled drinking water of Kathmandu valley. Int J Infect Microbiol. 2012;1:84–6.
  191. 191. Tsai GJ, Yu SC. Microbiological evaluation of bottled uncarbonated mineral water in Taiwan. Int J Food Microbiol. 1997;37:137–43. pmid:9310848
  192. 192. Uravashi VD, Goyal M, Purohit SK. Physical, chemical and microbiological analysis of bottled water. J Vet Publ Hlth. 2004;2:67–9.
  193. 193. Varga L. Bacteriological quality of bottled natural mineral waters commercialized in Hungary. Food Control. 2011;22:591–5.
  194. 194. Vidal JD, Consuegra AS, Gomescaseres LP, Marrugo JN. Evalución de la calidad microbiológica del agua envasada en bolsas producida en Sincelejo—Colombia. Rev MZ Córdoba. 2009;14:1736–44.
  195. 195. Warburton DW, Dodds KL, Burke R, Johnston MA, Laffey PJ. A review of the microbiological quality of bottled water sold in Canada between 1981 and 1989. Can J Microbiol. 1992;38:12–9. pmid:1581861
  196. 196. Warburton D, Harrison B, Crawford C, Foster R, Fox C, Gour L, et al. A further review of the microbiological quality of bottled water sold in Canada: 1992–1997 survey results. Int J Food Microbiol. 1998;39:221–6. pmid:9553800
  197. 197. Warburton DW, Peterkin PI, Weiss KF, Johnston MA. Microbiological quality of bottled water sold in Canada. Can J Microbiol. 1986;32:891–3. pmid:3545409
  198. 198. Wendpap LL, Dambros CSK, Lopes VLD. Qualidade das águas minerais e potável de mesa, comercializadas em Cuiabá-MT. Hig Aliment. 1999;13:40–4.
  199. 199. Yamaguchi MU, Rampazzo RCP, Yamada-Ogatta SF, Nakamura CV, Ueda-Nakamura T, Filho BPD. Yeasts and filamentous fungi in bottled mineral water and tap water from municipal supplies. Braz Arch Biol Technol. 2007;50:1–9.
  200. 200. Yasin N, Shah N, Khan J, Saba N, Islam Z. Bacteriological status of drinking water in the peri-urban areas of Rawalpindi and Islamabad-Pakistan. African J Microbiol Res. 2012;6:169–75.
  201. 201. Yousaf S, Chaudhry MA. Microbiological quality of bottled water available in Lahore City. J Pak Med Stud. 2013;3:110–3.
  202. 202. Zeenat A, Hatha AAM, Viola L, Vipra K. Bacteriological quality and risk assessment of the imported and domestic bottled mineral water sold in Fiji. J Water Health. 2009;7:642–9. pmid:19590131
  203. 203. Higgins JPT, Green S. Cochrane Handbook for Systematic Reviews of Interventions. The Cochrane Collaboration; 2011.
  204. 204. Stoler J, Fink G, Weeks JR, Otoo RA, Ampofo JA, Hill AG. When urban taps run dry: Sachet water consumption and health effects in low income neighborhoods of Accra, Ghana. Health Place. 2012;18:250–62. pmid:22018970
  205. 205. Ghana Statistical Service. Ghana Multiple Indicator Cluster Survey. Accra: 2012.
  206. 206. National Bureau of Statistics. Nigeria—Multiple Indicator Cluster Survey, 2011. Main Report. Abuja: 2013.
  207. 207. Bradley DJ, Bartram JK. Domestic water and sanitation as water security: monitoring, concepts and strategy. Phil Trans R Soc A. 2013;371:20120420. pmid:24080628
  208. 208. Cronk R, Slaymaker T, Bartram J. Monitoring drinking water, sanitation, and hygiene in non-household settings: Priorities for policy and practice. Int J Hyg Environ Health. 2015.
  209. 209. Bartram J, Cronk R, Montgomery M, Gordon B, Neira M, Kelly E, et al. Lack of toilets and safe water in health-care facilities. Bull World Health Organ. 2015;93:210. pmid:26229180
  210. 210. Howard G, Bartram J. Domestic water quantity, service, level and health. Geneva: World Health Organization; 2003.
  211. 211. Barrell RA, Hunter PR, Nichols G. Microbiological standards for water and their relationship to health risk. Commun Dis Public Heal. 2000;3:8–13.
  212. 212. Bischofberger T, Cha SK, Schmitt R, König B, Schmidt-Lorenz W. The bacterial flora of non-carbonated, natural mineral water from the springs to reservoir and glass and plastic bottles. Int J Food Microbiol. 1990;11:51–71. pmid:2223521
  213. 213. Hunter PR. The microbiology of bottled natural mineral waters. J Appl Bacteriol. 1993;74:345–52.
  214. 214. Bartram J, Cotruvo J, Exner M, Fricker C, Glasmacher A. Heterotrophic Plate Counts and Drinking-water Safety: The Significance of HPCs for Water Quality and Human Health. Geneva: 2003.