PWAT-D-25-00054

An assessment of household water handling practices on microbial water quality in Kibera informal settlement, Nairobi, Kenya.

PLOS Water

Dear Dr. Musyoka,

Thank you for submitting your manuscript to PLOS Water. After careful consideration, we feel that it has merit but does not fully meet PLOS Water's publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses all the comments raised by the reviewer.

In addition to the reviewer’s points, I have also included some comments and suggestions for your consideration:

1. A major limitation of the study is the absence of microbial contamination testing at each point of water collection (i.e., the water kiosk). This omission makes it difficult to assess the extent of contamination introduced during household storage and limits the ability to compare water quality across the three villages. It may also influence the interpretation of some of other significant relationships reported in the study. The discussion should more clearly articulate why this limitation does not compromise the validity of your findings. Your response to this issue will play a critical role in the decision regarding the acceptance of your manuscript.

2. Several parameters (electrical conductivity, pH, and fluoride concentrations), were measured; however, these data are either not presented or only briefly mentioned in the manuscript. It would have been informative, for instance, to examine whether significant differences in these parameters exist among households from the three villages.

3. In M&M, additional details are needed on the three selected villages (Laini Saba, Makina, and Soweto West), such as the estimated number of inhabitants and other relevant demographic or contextual information.

4. Was it possible to determine whether there is a relationship between the water storage time in households (time after collection) and the distance between the water source and the household (time to fetch water)?

5. How do you explain the absence of a significant relationship between self-reported diarrhea in the past 7 days and microbial water quality?

6. Overall, the discussion is very brief and lacks a thorough critical analysis of the results. Furthermore, it references only a limited number of published studies relevant to the topics addressed in your manuscript.

Please submit your revised manuscript by Jul 06 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at water@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pwat/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

We look forward to receiving your revised manuscript.

Kind regards,

Jean-François Humbert

Academic Editor

PLOS Water

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Additional Editor Comments (if provided):

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Reviewers' comments:

Reviewer's Responses to Questions

-->Comments to the Author

1. Does this manuscript meet PLOS Water’s publication criteria? Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe methodologically and ethically rigorous research with conclusions that are appropriately drawn based on the data presented.-->

Reviewer #1: Partly

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-->2. Has the statistical analysis been performed appropriately and rigorously?-->

Reviewer #1: I don't know

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-->3. Have the authors made all data underlying the findings in their manuscript fully available (please refer to the Data Availability Statement at the start of the manuscript PDF file)?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception. The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.-->

Reviewer #1: No

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-->4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS Water does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.-->

Reviewer #1: Yes

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-->5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)-->

Reviewer #1: This is an extremely important topical area of research and addresses a lack of information for global health and vulnerable populations facing compromised water quality. However, there are a number of areas to clarify ethical concerns, transparency of research, and context/relevance of results within the larger research framework. I made a number of comments in red in the attached PDF, but will summarize major points by area below:

1) Title- Not very descriptive or specific- I strongly recommend a more rigorous title that will attract more views to your paper, as well.

2) Abstract- need more details in terms of context and relevance in abstract. The results should be discussed/interpreted a bit more to emphasize relevance. Also, please clarify details of recruitment/enrollment a bit more (I know it was random selection- but that does describe how you randomly selected or how participants were enrolled- did you just approach?, or compensated).

3) The intro is a bit lacking in some detail (With respect to the region studied and what is known about water quality and health, as well as types of water treatment/handling) and structure (make sure to have a clear intro sentence to clarify what each paragraph details).

4) Methods: It would be good to have two schematics: a) overall study design/flow b) how you carried out data analysis, to make this section and the study easier to understand.

(i) I have some ethical concerns about engagement with the study participants-- how did you recruit them? was compensation provided? did you provide them with results? any suggestions as to how to treat the water properly (e.g. best WASH practices overall)? Any treatment options?

(ii) I am glad quenching was done-- but why did you not measure the chlorine again at the time of the microbial analysis?

(iii) the fluoride measurement just thrown in there without any description of why or the purpose.

(iv) overall, there is a lot of description of the details of the test processes/kits that could just be referenced (or put in an appendix).

(v) It would be good to include the survey tool as an appendix.

(vi) break down last section into data management/quality assurance and data analysis, respectively

See ethical concerns - and queries for more info (it would also be helpful to include the consent sheet as an appendix)

5) Results - Please provide raw data and any code used to analyze it. I also think I follow most of how you carried out your analysis and rationale- but a schematic would be helpful for the reader -- and to make sure there were no erroneous assumptions. Also, I am also a little concerned about the potential time delay b/w the FCR measurements were done and the time when microbial analysis was done (even with the quenching done).

6) Discussion- Please see comments on contextualizing the data/findings in larger context- I put in a number through out the section. Would strongly recommend additional citations to existing work.

7) Conclusion- Be more specific as to what new information is provided in this manuscript, and why it matters--- Also, the last sentence is a run on and incomplete.

Hope you can make these changes and that they are helpful. I think it will provide a better context and framework for this excellent (And ambitious) work!

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Reviewer #1: Yes:  Amber Roegner

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While revising your submission, please upload your figure files to the Preflight Analysis and Conversion Engine (PACE) digital diagnostic tool, https://pacev2.apexcovantage.com/. PACE helps ensure that figures meet PLOS requirements. To use PACE, you must first register as a user. Registration is free. Then, login and navigate to the UPLOAD tab, where you will find detailed instructions on how to use the tool. If you encounter any issues or have any questions when using PACE, please email PLOS at figures@plos.org. Please note that Supporting Information files do not need this step.

Attachments

Attachment

Submitted filename: PWAT-D-25-00054_reviewer_comments.pdf

PWAT-D-25-00054R1

Household water handling practices and microbial water quality in informal settlements of Kibera, Kenya

PLOS Water

Dear Dr. Musyoka,

Thank you for submitting your manuscript to PLOS Water. After careful consideration, we feel that despite the numerous improvements made to the manuscript, it does not fully meet PLOS Water's publication criteria. I am in full agreement with the reviewer and believe that the discussion should be further developed regarding the three points raised. In particular, I'm not fully convinced by your responses on the lack of a significant relationship between self-reported diarrhea and microbial water quality. I don’t understand why you wrote, “The relationship between diarrhea and water quality is well established, and studies have often analyzed water quality as a predictor of diarrheal disease (outcome),” and then stated, “The absence of a significant relationship is consistent with this logical assumption.” To me, if the relationship between diarrhea and water quality is well established, one would expect to find a significant correlation between these two variables in your data? Similarly, your response concerning the absence of microbial contamination testing at each water collection point requires further improvement. Please take into account the reviewer’s suggestion on this critical issue.

Please submit your revised manuscript by Oct 16 2025 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at water@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pwat/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A rebuttal letter that responds to each point raised by the editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

We look forward to receiving your revised manuscript.

Kind regards,

Jean-François Humbert

Academic Editor

PLOS Water

Journal Requirements:

If the reviewer comments include a recommendation to cite specific previously published works, please review and evaluate these publications to determine whether they are relevant and should be cited. There is no requirement to cite these works unless the editor has indicated otherwise.

Additional Editor Comments (if provided):

Reviewer #1:

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Reviewers' comments:

Reviewer's Responses to Questions

-->Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.-->

Reviewer #1: (No Response)

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-->2. Does this manuscript meet PLOS Water’s publication criteria? Is the manuscript technically sound, and do the data support the conclusions? The manuscript must describe methodologically and ethically rigorous research with conclusions that are appropriately drawn based on the data presented.-->

Reviewer #1: Partly

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-->3. Has the statistical analysis been performed appropriately and rigorously?-->

Reviewer #1: Yes

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-->4. Have the authors made all data underlying the findings in their manuscript fully available (please refer to the Data Availability Statement at the start of the manuscript PDF file)?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception. The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.-->

Reviewer #1: Yes

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-->5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS Water does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.-->

Reviewer #1: Yes

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-->6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)-->

Reviewer #1: Major comments

Overall, the manuscript is much improved with the abstract more succinct and specific, the methods clarified substantially, and the results and findings presented more clearly. Thanks for all the hard work on the updates.

There are still a couple of discussion and conclusion points to clarify or elaborate:

1. Other treatment options beyond chlorination: I believe theoretically the Sawyer filters should remove E coli (If they are the ones with which am familiar with) – might there be other ways to improve outcomes with these that you could discuss? Perhaps longevity of use, proper use, pre filtration, etc., as well as the potential for contamination after the filter’s use. Since part of the discussion/emphasis is that chlorination has a more favorable outcome (e.g. lower microbial contamination), it would be important to discuss some suggestions that could be made that might make boiling or sawyer filters more effective. There could also be public health sector policy or educational initiatives as a result as you indicate in lines 343-345 (“There is an urgent need to reassess the effectiveness of non-chlorine- based water treatment methods in slum settings. This assessment could inform changes in policy and practice, enabling public health actors to establish water treatment strategies that are not only effective but also offer sustained protection against microbial contamination.”) Therefore, I think it is important not to dismiss these other options (particularly since the taste can be a reason households elect NOT to treat with chlorination- might want to discuss that, as well).

2. Clarification of discussion around lack of link b/w microbial water quality and self-reported diarrhea- I understand that the thrust of the manuscript was not focused on health outcomes, but ultimately, that is the underlying concern, no? That is why public health officials want to encourage both better provision of water sources and WASH practices in the household? To the point of below, I think you could look at why the WQ was not a predictor of diarrhea if that is the “usual predictor”—and discuss other factors that would influence/obfuscate incidence of diarrhea (related to how and when the water source was take and potential other WASH practices- you have some of them that you could explore, as well). But regardless, since one would expect some sort of association between microbial contamination and household diarrhea, a more robust and not dismissive discussion is needed. I would modify lines 335-337.

3. Discussion/emphasis on inability to identify point of contamination: To the editor’s last review priority, there is still a need to emphasize or highlight the major limitation of not testing the microbial in water at multiple time points (or free chlorine concentration for that matter) –at the source water, in the household prior to treatment, post treatment, and at point of use. Your argument, I believe, is that the chlorination is the most effective treatment because it is the only one that guarantees sustained treatment until consumption, but without looking at other time points and mitigating factors (for example, did households with chlorination, just do a better job of cleaning out vessels, cleaning taps for dispensing, avoiding contamination of containers for drinking, having better overall WASH practices), I don’t think you can definitively make that conclusion. Similarly, the differences in percentages of contamination across regions needs to have the caveat that we don’t know when the contamination occurred.

It seems like the major finding is that households with chlorination had lower odds of microbial contamination at the tap, whereas the households with boiling and filters had the same or higher odds, respectively. That seems like an important finding for the region but needs a more robust discussion or clarification as to where the discrepancies may lie, why, and what public health (or water quality providers) could do about it. In addition, there are situations with distribution centers chlorinate water before sending it out to the households, so that might warrant discussion given: “The study focused on improvement of services by the Nairobi City Water and Sewerage Company.”

Minor edits

- Make sure to italicize species and genus names, e.g. Escheria coli (sometimes done, just not consistently)

- Line 20 – extra space at start of sentence beginning with “We…" and Line 22- prior to “Most…”

- Line 252 – space needed in 0.2mg/L

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-->7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

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Reviewer #1: No

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PWAT-D-25-00054R2

Household water handling practices and microbial water quality in informal settlements of Kibera, Kenya

PLOS Water

Dear Dr. Musyoka,

Thank you for submitting your manuscript to PLOS Water. After careful consideration, we feel that it has merit but does not fully meet PLOS Water's publication criteria as it currently stands. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Please submit your revised manuscript by Jan 17 2026 11:59PM. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at water@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pwat/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

Please include the following items when submitting your revised manuscript:

• A letter that responds to each point raised by the editor and reviewer(s). You should upload this letter as a separate file labeled 'Response to Reviewers'.
• A marked-up copy of your manuscript that highlights changes made to the original version. You should upload this as a separate file labeled 'Revised Manuscript with Track Changes'.
• An unmarked version of your revised paper without tracked changes. You should upload this as a separate file labeled 'Manuscript'.

Guidelines for resubmitting your figure files are available below the reviewer comments at the end of this letter.

We look forward to receiving your revised manuscript.

Kind regards,

Michael B. Fisher

Academic Editor

PLOS Water

Journal Requirements:

If the reviewer comments include a recommendation to cite specific previously published works, please review and evaluate these publications to determine whether they are relevant and should be cited. There is no requirement to cite these works unless the editor has indicated otherwise.

Please review your reference list to ensure that it is complete and correct. If you have cited papers that have been retracted, please include the rationale for doing so in the manuscript text, or remove these references and replace them with relevant current references. Any changes to the reference list should be mentioned in the rebuttal letter that accompanies your revised manuscript. If you need to cite a retracted article, indicate the article's retracted status in the References list and also include a citation and full reference for the retraction notice.

Additional Editor Comments (if provided):

This work appears to be a valuable and interesting study of the physical, chemical, and microbial characteristics of household stored drinking water in several sections of Kibera. Several improvements can strengthen this work. Some of these are specified in the comments of Reviewer 1, and should be incorporated more completely. This is particularly true with respect to the comments regarding inclusion of recruitment methods and details, the inclusion of survey tools and instruments in Supporting Information, and the inclusion of references to additional relevant prior work on household drinking water quality in Kibera and other informal settlements in low- and middle-income country settings. More completely taking these commends onboard can strengthen this work.

In addition, a few other edits and revisions to the methods, results, discussion, and conclusions could strengthen this work further:

The methods appear to be potentially suitable, but some methodological details and potentially interesting results appear not to be included. Including these where possible, and mentioning their absence in a discussion of limitations where not possible to include them, could better enable reviewers to assess the validity of this work.

A few potential relevant methods details include:

Methods:

Sample size calculations: how did the authors determine the number of households to sample at each water point, the numbers of water points to sample in each section of Kibera and, most importantly, how did the authors calculate the sufficiency of this sample to answer their research question with sufficient statistical power? If this was done, please provide the relevant calculations. If it was not done, please address this point in a "Limitations" section in the discussion.

E. coli and total coliform enumeration methods: the authors state that: "The membrane filtration method was used to detect and enumerate Escherichia coli and total coliform." This is not sufficient detail to evaluate the suitability of the methods. Ideally, a published standard method was followed that can be referenced, such as EPA Method 1604, etc. If so, please list and cite the standard method, and note any deviations from the published method (for example, the use of HiCromeTM Chromogenic Coliform agar (Himedia, India), if applicable. While reviewer 1 rightly suggested streamlining certain methods details, it is very important to specify the selective chromogenic or fluorogenic agar or broth medium used for membrane filtration assays, since many different such media exist, and different media can yield different results under different conditions. I would therefore suggest streamlining these methods while clearly defining the standard published method used and the specific defined culture medium used, at a minimum. Please note that if you or your colleagues have previously described the precise methods you used in another publication, it is fine to cite that publication, but helpful to briefly summarize the above methods details (standard method followed and defined culture medium used) anyway. These details will enable readers to more easily verify that suitable methods were used in this work, and will remove any doubts from the minds of potential reviewers as to the validity of these methods.

Method detection limits for E. coli and total coliform quantitation should also be stated here- what were the lower (presumably 1 CFU/100mL) and upper limits of detection of the methods used to detect and quantify E. coli and total coliforms (collectively fecal indicator bacteria, or FIB)? Were samples diluted in any way prior to analysis, or were all samples analyzed undiluted?

Inclusion of seasonality and/or rainfall data is probably very important. FIB occurrence in drinking water can vary greatly with rainfall (Kostyla, C., Bain, R., Cronk, R., & Bartram, J. (2015). Seasonal variation of fecal contamination in drinking water sources in developing countries: a systematic review. Science of the Total Environment, 514, 333-343.). It is helpful to know if data were collected in rainy or dry seasons, and if and when rainfall occurred during data collection. Where these data are available, they might ideally be included. If they were not collected, they may still be obtained from meteorological stations, national weather services, or remote sensing data platforms. Inclusion of rainfall data, particularly if some samples were collected shortly after rainfall events, could greatly strengthen this work. Rainfall is often a very strong predictor of FIB occurrence in drinking water, and should ideally be included in univariable and multivariable analyses, if feasible. If not feasible, this should be addressed in a "Limitations" section.

Quality assurance methods, including the use of blanks and field duplicates are described in the methods section. The results of these QC checks should be reported somewhere. What proportion of blanks and duplicates were within tolerances, and what acceptance tolerances were used for blanks and duplicates in this work? What water was used for blanks, and how was it prepared? Were blanks prepared and analyzed in the lab or in the field, or both? If field duplicates were analyzed but no field blanks were collected (blanks transported to the field, collected in the same manner as actual samples, then transported back to the lab and analyzed), this should be noted in a "Limitations" section.

Data analysis: if data were analyzed in STATA, it might be helpful to provide the STATA code used as a file in Supporting Information. In addition, it might be helpful to provide the cleaned raw dataset used, after deidentifying the data by stripping any GPS coordinates, names, household identifiers, and other potentially identifiable personal data from the file. If such a deidentified raw dataset can be included in supporting information, it can add credibility to the analysis done in this work, and make the data available for future potential additional analysis or meta-analysis, etc.

Results:

The results of this work are interesting and in many cases they are reported in a clear manner. However, many possible results that could be reported appear to be missing. Specifically: it would be helpful to present numeric data for E. coli and Total coliforms in addition to the binary presence/absence data. Often, it can be useful to tabulate these CFU/100mL data in terms of WHO risk categories for FIB, as described in the WHO Guidelines for Drinking-Water Quality (i.e., <1 CFU/100 mL corresponds to low risk; 1-10 corresponds to intermediate risk; etc....). If the patterns of quantitative FIB occurrence (either as CFU/100 mL or as categorical data with respect to WHO risk categories) are different from the patterns of binary presence/absence data, this might be noted.

Similarly, it would be interesting to report numeric free chlorine residual data, if possible, in addition to the binary data on whether FC>0.2 mg/L.

Furthermore, the authors report collecting turbidity data but these data do not appear to be reported in the Results section. It would be very interesting to see these data reported in the results section and included in the univariable and/or multivariable analyses. The authors report conductivity data, but these are not included in regressions. It would be interesting to see some analysis of turbidity and/or conductivity data as potential proxies for contamination and/or intrusion of piped treated water by untreated water, etc. If no such association exists, or if these data were excluded for other reasons, this can be stated. If the data are usable but simply do not have meaningful associations with any outcomes of interest, this could be presented in univariable and/or multivariable regressions, either in the Results section or in Supporting Information.

Finally, while the authors describe the justification for excluding potential explanatory variables that were not significant in univariable regressions at the 95% confidence level, it would be interesting to report the results that would be obtained if a higher threshold (say p< 0.20) were used for inclusion/exclusion of variables. Likewise, while this rationale makes sense for inclusion of potential explanatory variables, it may not make sense to exclude potential covariates that are included not as potential explanatory factors but rather because they may influence the relationship between your main independent variables and your outcomes of interest. Examples of potential covariates could include proxies for wealth, such as owning vs renting a dwelling, demographic characteristics such as household size, etc...

The exclusion of floor material from the regression analyses was also confusing. It is unclear whether this variable should be included as an independent variable, a covariate, or excluded. However, some rationale should be provided by the authors for the treatment of this variable, and it may be helpful to include in in analyses unless a strong case can be made for exclusion.

Other variables that would have been helpful to include might be the presence or absence of domestic animals/livestock in the home or household area, and/or whether they are in enclosures or not. While these data may not have been available, it may be useful to mention in a Limiations section that other studies have included these data and found them relevant, and their inclusion in the current work could have been relevant.

Similarly, previous studies have found strong associations between microbial water quality in household stored water and the diameter of the opening of the storage container (specifically, whether or not it is large enough to remove water by dipping and scooping- see Mintz et al [Mintz, E. D., Reiff, F. M., & Tauxe, R. V. (1995). Safe water treatment and storage in the home: a practical new strategy to prevent waterborne disease. Jama, 273(12), 948-953.]), and observations of how the household members extract water when providing it for sample collection (pouring, dipping, scooping, etc.)- CF Fisher, M. B., Danquah, L., Seidu, Z., Fechter, A. N., Saga, B., Bartram, J. K., ... & Ramaswamy, R. (2020). WaSH CQI: Applying continuous quality improvement methods to water service delivery in four districts of rural northern Ghana. PloS one, 15(7), e0233679.. If these data were collected, it would be helpful to report them and include them in analyses. If not, it would be helpful to note their absence in a "Limitations" section.

Finally, while the bivariate analyses of the data are useful and interesting, it might also be interesting to look at ordinal logistic regressions of the data, with FIB concentration structured in terms of WHO risk categories rather than as binary presence/absence data. If such regressions do not yield usable results, or yield results that are largely similar to the binary results, they may be included in supporting information. If they yield usable and different results, the differences could be presented and discussed.

Discussion:

The discussion touches on many key points, but lacks structure and does not include some potentially useful elements such as a clear presentation of the current results in the context of prior work, and a thorough discussion of the limitations of the study. I encourage the authors to include both of these items. A useful structure for the discussion might include some of the following sections:

1) Summary of the main findings of the study

2) Contextualization of these findings with respect to the relevant literature- what is new that we have learned from this work- many studies of drinking water quality in informal communities exist- what is especially new and useful in the current work?

3) Interpretation of main findings, discussion of unexpected findings (e.g. the apparent counterintuitive positive association between filter use and FIB occurrence, etc.), and discussion of potential explanations for unexpected or inconclusive findings (including the possibility that biofilms may form on/in filters and increase apparent FIB occurrence, or that households may be more likely to use filters when their source water is heavily contaminated already, etc...- cite relevant literature to support any such speculations, if possible).

4) Discussion of limitations of this work, and their potential impact on the results and conclusions (this is especially important)

5) Recommendations for policy, practice, and further research (as applicable)

6) Conclusions (if appropriate).

Note that a few things may be helpful to note in the "Limitations" section of your discussion:

1) This study examined FIB as an outcome, but did not quantify the occurrence of enteric viruses, protozoan cysts, or other pathogens. This is important because the strong association between free residual chlorine and FIB may not necessarily indicate an equally strong association with other pathogens of health concern, especially protozan cysts, etc. Similarly, removal of FIB by filters may be much more efficient than removal of human enteric viruses. Finally, associations between FIB occurrence and self-reported diarrhea may in part be weak if unobserved pathogens (e.g. viruses, parasites) are strong contributors to diarrhea, and do not correlate very well with FIB occurrence in the study setting.

2) A discussion of seasonality is probably very important. FIB occurrence in drinking water can vary greatly with rainfall. It is helpful to know if data were collected in rainy or dry seasons, and if and when rainfall occurred during data collection. Where these data are available, they might ideally be included.

Conclusion:

The conclusions of this work could be greatly strengthened by a few things:

1) It is important to draw conclusions from this work in context. Many other studies have characterized household drinking water in informal settlements in low- and middle-income countries and found occurrence of FIB in some samples. It is important to specify what is new in the conclusions of your work that was not known previously, whether in specific reference to Kibera or in more general terms.

2) It is important to contextualize the association of residual chlorine with FIB in terms of the possible presence of unobserved pathogens such as viruses and parasites that may be less sensitive to chlorine than FIB.

3) It may be relevant to talk about the occurrence of FIB in stored drinking water both in terms of safe water storage and in terms of efforts under SDG 6 to expand access to 24/7 piped, adequately treated drinking water on premises that is available when needed and free from fecal contamination or priority chemical contaminants--- if the occurrence of contamination is related at least in part to unsuitable household water treatment and/or storage practices, and progress on SDG 6 may reduce the need for households to store and treat water if they can get safe piped water on demand, then this might be a useful point to reflect on in your discussion and conclusions.

Overall, this is good work that can be made much stronger if the above points can be addressed adequately, and the suggestions made by Reviewer 1 can be incorporated more fully.

Please let us know if any questions about the above points, or if we can provide any assistance in this process.

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Reviewers' comments:

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Household water handling practices and microbial water quality in informal settlements of Kibera, Kenya

PWAT-D-25-00054R3

Dear Mr Musyoka,

We are pleased to inform you that your manuscript 'Household water handling practices and microbial water quality in informal settlements of Kibera, Kenya' has been provisionally accepted for publication in PLOS Water.

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Thank you again for supporting Open Access publishing; we are looking forward to publishing your work in PLOS Water.

Best regards,

Michael B. Fisher

Academic Editor

PLOS Water

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Additional Editor Comments (if provided):

This is good work and a useful contribution to the field. Thank you for your patience.

Reviewer Comments (if any, and for reference):