https://orcid.org/0000-0002-5169-1521
Figures
Abstract
Very small islands in Indonesia face challenges in accessing clean water due to limited space for building water resource facilities, such as reservoirs. Most of the time, the inhabitants of these islands rely on rainwater and wells, which are not sustainable sources due to drought seasons and seawater intrusion. To address this issue, Seawater Reverse Osmosis (SWRO) can be implemented in these areas where seawater is abundant. However, there may be obstacles when applying SWRO systems in such environments. This study aimed to assess the capabilities of SWRO facilities, and the obstacles involved in evaluating clean water access on very small islands. We used a combination of structured questionnaires, interviews, and direct observations on two small islands in Indonesia, Belakang Padang Island and Labu Island. On Belakang Padang Island, we interviewed the water resource manager in October 2022 and March 2023 and surveyed 61 households in the Tanjung Sari subdistrict in October 2022. On Labu Island, we interviewed the staff of the SWRO system and surveyed 35 coastal households in September 2023. On both islands, the government improved residents’ access to clean water by constructing SWRO facilities in 2016 on Belakang Padang Island and in 2021 on Labu Island. However, on Belakang Padang Island, the system was not operational when we visited on March 15, 2023. The main obstacles were slow bureaucratic processes for repairs and maintaining the operation of SWRO facilities. These problems need to be addressed before expanding the implementation of this system to other very small islands in Indonesia.
Citation: Savitri A, Souma K, Ishidaira H, Magome J (2024) Field survey for assessing seawater reverse osmosis (SWRO) applications on very small islands in Indonesia. PLOS Water 3(11): e0000241. https://doi.org/10.1371/journal.pwat.0000241
Editor: Ilunga Kamika, University of South Africa, SOUTH AFRICA
Received: May 7, 2024; Accepted: October 16, 2024; Published: November 15, 2024
Copyright: © 2024 Savitri et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Data Availability: Datasets for this research are available in this paper.
Funding: This study was supported by the Japan Society for the Promotion of Science (KAKENHI grant nos. JP19H02246 and JP19H01378 to KS) and by the “Nagoya University High Performance Computing Research Project for Joint Computational Science” and HPCI System Research Project (Project ID: hp210291 to KS) in Japan. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing interests: The authors have declared that no competing interests exist.
Introduction
The global demand for water is growing annually (Fig 1) [1, 2]. Ensuring universal access to clean water (water that can be used for at least hygiene and sanitation purposes) by 2030 is target 6.1 of the United Nations Sustainable Development Goals. However, not all countries are positioned to achieve this goal for various reasons, including population growth and unequal infrastructure distribution [3, 4]. The 2015 Paris Agreement acknowledges that small islands are particularly vulnerable to climate change. Small island states face scarce freshwater sources, fluctuating weather patterns, rising sea levels, extreme weather events linked to climate change, and expanding populations [5, 6]. Based on Chapter 15 of the Intergovernmental Panel on Climate Change 2022 report, small islands are increasingly impacted by temperature increases, tropical cyclones, storm surges, droughts, shifting precipitation patterns, rising sea level, coral bleaching, and invasive species [7]. Many small islands lack sufficient fresh water supplies to meet residential, commercial, and agricultural needs [8]. On small islands, water supplies may include groundwater, surface water, ocean water desalination, and sparingly harvested rainwater; [9] the restricted availability of water resources poses challenges to development on small islands [10]. Furthermore, the effects of climate change and seawater intrusion present risks to groundwater resources on small islands. Overall, water treatment solutions must cater to the unique potential and challenges of each small island.
(Left) water withdrawal. (Right) water consumption.
Indonesia is a Southeast Asian country comprising 17,508 islands, 16,671 of which are officially recognized by the United Nations, located between the Indian and Pacific Oceans [11]. According to climate change projections, rising temperatures and shifting rainfall patterns will gradually reduce the amount of water availability in the majority of the Indonesian Archipelago, especially in small islands [12]. Provinces on Java-Bali Island typically have better access to potable water and sanitation conditions for their households compared to other islands [13]. Due to the political process of centralization of public services and administration that occurred in the 1980s and 1990s. While some regions have developed, others have been left behind in development throughout Indonesia [14]. Only 20% of households in Indonesia have access to clean water managed by the central government [15]. The availability of clean water in rural areas or small communities tends to rely on natural clean water sources and is not well managed [16].
During the dry season, hinterlands and small islands have limited access to clean water due to low water availability [17, 18]. However, there are few comprehensive studies on the state of water resources on very small islands (less than 100 km2), [19–21] particularly in Indonesia, where governments tend to focus efforts on larger islands such as Java [22–25]. Indonesia is committed to achieving SDG 6 of the 2030 Agenda for Sustainable Development, which is to ensure universal access to safe drinking water and sanitation. The SDG targets have also been incorporated into the national targets in the 2020–2024 Rencana Pembangunan Jangka Menengah Nasional (National Medium-Term Development Plan) [26]. One strategy adopted by local governments to meet clean water needs is the installation of seawater reverse osmosis (SWRO) systems [27]. Previous studies have focused on desalination facilities on tourist islands [28–30]. A previous study investigated SWRO systems in a few regions of Indonesia; however, these systems were located far apart and/or near tourist destinations [31]. By contrast, small islands on the periphery of Indonesia may be less economically profitable but must still be safeguarded to maintain the integrity of Indonesia’s international borders.
The aim of the present study was to assess the capability of the SWRO facilities and the other sources of clean water and obstacles to meeting clean water demands on very small islands. We compared the state of freshwater sources on two very small Indonesian islands located closed to one another near Malaysia and Singapore; because of their proximity, the two islands experience similar rainfall patterns.
Materials and methods
Study sites
We surveyed two very small islands, Belakang Padang Island and Labu Island, Riau Islands Province, Indonesia (Fig 2). Riau Islands Province is bounded by Vietnam and Cambodia to the north, Malaysia and West Kalimantan Province to the east, Bangka Belitung and Jambi Islands Provinces to the south, and Singapore, Malaysia, and Riau Province to the west. Riau Islands Province contains five regencies, two cities, 52 subdistricts, and 299 villages across a total of 2,408 large (> 2,000 km2) and small islands (< 2,000 km2); of these islands, 30% are unnamed and unpopulated [32, 33]. Riau Islands Province is located on one of the world’s busiest shipping lanes along the Malacca Strait and Natuna Sea (South China Sea).
The areas of Labu Island and Belakang Padang Island are 0.188 km2 and 2.317 km2, respectively [34]. Both islands fall under the administration Batam Island, which is the most developed island in Riau Islands Province. Belakang Padang Island is under the jurisdiction of Belakang Padang District, which includes several islands northeast of Batam Island. In this study, Belakang Padang Island refers specifically to the island that contains the Tanjung Sari and Sekanak Raya Subdistricts. This island was chosen because it is the most underdeveloped island in the Belakang Padang District. In contrast, Labu Island is part of Bulang District, located southeast of Batam Island.
The two islands have different access to water. On Belakang Padang Island, inhabitants have multiple sources of water. Most water is obtained from the SWRO facility and a reservoir, with pipelines (made from high density polyethylene) connecting the SWRO facility and the reservoir to residents’ homes. In 2019, 23% of residents were connected to the SWRO system, 34% to the reservoir, and only 2% were connected to both [31]. Additionally, some communities and households have rainwater tanks to collect water during the wet season. However, during the dry season, Belakang Padang Island experiences limited access to clean water due to a lack of rainfall [31, 35]. When the SWRO facility and reservoir cannot meet the water demand, inhabitants must purchase water from other islands [31]. In contrast, the inhabitants of Labu Island rely solely on the SWRO facility, which is connected to their homes, to meet their water needs. Currently, the water resources on both islands are managed by the Regional Public Service Agency Integrated Service Unit for the Clean Water Program (Badan Layanan Umum Daerah Unit Pelayanan Terpadu Program Air Bersih; BLUD UPT PAB) Batam.
We used a combination of closed-ended structured questionnaires and interviews, along with direct observations of water facilities on both islands to collect data.
Water resource manager interviews
We obtained information about the state of water resources and government initiatives through direct interviews with local water resource managers on Belakang Padang Island and Labu Island. The interview questions are listed in Table 1. The water resource manager on Belakang Padang Island was interviewed based on the question in Table 1 for two days on October 2, 2022, and March 15, 2023. The survey was conducted twice because, during the first interview, the SWRO system was not operational. The second survey was carried out to reconfirm the previous responses and to check whether the SWRO system had resumed normal operation. The staff of the SWRO facility on Labu Island were interviewed for one day on September 19, 2023. We also met with staff from Balai Besar Wilayah Sungai (River Basin Organization; BWWS) Sumatra IV in one day, which manages water resources in Riau Islands Province, on September 20, 2023. Prior to conducting the interviews, we verbally requested consent to use the data for our research in local language.
Resident interviews
We conducted questionnaire interviews of households on Belakang Padang Island and Labu Island. We posed 20 questions (Table 2) to the head of the household on four topics: house condition, socioeconomic conditions, clean water and sanitation, and environmental conditions around the house. We interviewed 35 households, which were all households, in a coastal area of Labu Island for one day on September 21, 2023. On Belakang Padang Island, we determined a cluster of households and interviewed 61 households inside of the cluster in the Tanjung Sari subdistrict, Kampung Tengah RT No. 002/RW No. 002, on October 3, 2022 for one day (Figs 3 and 4); The Kampung Tengah has the worst living environment on Belakang Padang Island, and is impacted by tides due to its proximity to the ocean. Prior to conducting the interviews and field surveys, we asked for permission from the leader of the district (Kecamatan Belakang Padang), and we also verbally requested consent to use the data for our research in local language from head of neighborhoods and from all participants, with the head of neighborhoods acting as a witness to the process. Additional information regarding the ethical, cultural, and scientific considerations specific to inclusivity in global research is included in the Supporting Information (S1 Text).
Results
Water resource manager interviews
Belakang Padang Island.
Based on water resource manager in Belakang Padang Island, the government constructed the small Sekanak Reservoir I (capacity around 540,000 m3) in the 1990s to meet the demand for clean water on Belakang Padang Island; this reservoir was later expanded with the construction of Sekanak Reservoir II (capacity around 460,000 m3) to meet growing water demand. Because these reservoirs rely solely on rainwater, and water levels drop during the dry season, the local community has frequently struggled to access clean water during the dry season (the reservoir volume is reduced by around 50% of their capacity). In response to a severe drought in 2016, which caused hardship to the community, the government built an SWRO facility on Belakang Padang Island that has been operating since 2017; this facility converts seawater into freshwater (hereafter, SWRO water). However, the SWRO facility has experienced operational issues originating from its unstable electricity source; power disruptions have interfered with the high pressure pump and disrupted water desalination. Additionally, the high operational time (24 hours/day) contributed to the failure of the pump. The disruption occurred twice: the first instance was from 2019 to 2020, requiring 4–5 months for the system to become operational again [28]. The second disruption began in 2022, and the system was still not operational as of our visit on March 15, 2023. The water resource manager had submitted a repair request to the central government, but the bureaucratic process was significantly slow. Besides that, the procurement of replacement parts, which are ordered from overseas, takes a long time. It was impossible to desalinate seawater when the pump was unavailable. During these times, the management used water from the reservoir and treated it with coagulation and ultrafiltration through the SWRO system before distributing it to households.
The SWRO water costs more than IDR 41,000 per m3, which is expensive for residents that had an average monthly income of IDR 2,852,000/month or around IDR 34,2 million per year; to help offset this expense, the central government subsidizes 50% of the cost. The SWRO system produces potable water that can be consumed directly within the facility; however, water produced by the SWRO system that is transported by pipe networks (made from high-density polyethylene) to households should not be consumed directly (The inhabitants reluctant to use water from SWRO facility as drinking water). The SWRO facility was originally intended to meet the water needs of residents living at higher elevations, which cannot be supplied by pipes from the reservoirs. However, other communities wanted access to SWRO water to supplement the reservoir water; by 2022, 852 houses were connected to the SWRO facility. However, the production capacity of the SWRO facility could only support 400–500 households. As a result, the SWRO facility needed to operate 24 hours per day.
Labu Island.
Before 2022, the residents of Labu Island had no local water source; they had to travel to other islands to either purchase water or collect it from rivers. The water was transported on small wooden boats, posing a risk to the residents’ safety. Fishermen/women had concerns about leaving their families without access to water while they worked. The community requested assistance from the government to provide a clean water source on their island; however, the island was too small to build a reservoir and the groundwater too poor—being murky and having an unpleasant odor—for wells, as observed by the inhabitants, making them reluctant to use it.
The SWRO facility on Labu Island was constructed on land donated by residents and began operation in 2022. The SWRO facility provides 24-hour access to clean water that meets the standards of the Indonesian Ministry of Health (The parameter standard can be seen at S1 Table). All Labu Island residents (population: 50 people in 2023) have access to SWRO water, although some continue to purchase water elsewhere. Since the start of operation, no major operational problems have occurred. SWRO water price is more than IDR 44,000 per m3; to help offset the expense, the central government subsidizes 50% of the cost. Overall, the community has benefited greatly from the SWRO facility as they no longer need to travel to other islands to access clean water.
Resident interviews
House condition.
On Belakang Padang Island, among the 61 households of Kampung Tengah interviewed, 82% of the houses were constructed of wood and built on stilts and 18% of the houses were constructed of concrete (S1 Fig). Approximately 80% of the houses required repairs to fix weakening structures that caused the buildings to tilt. Moreover, 84% of the houses lacked a septic tank and had inadequate toilets; only 16% of houses had a septic tank.
On Labu Island, among the 35 coastal-area households interviewed, 100% of the houses were built on stilts and lacked a septic tank. Some houses were aging and required repairs. The mosque and health center, located at the center of the island, both have septic tanks. In 2023, the government announced plans to build communal septic tanks, allocating one septic tank for every three to four houses.
Socioeconomic conditions.
The socioeconomic conditions of the communities of Belakang Padang Island and Labu Island tended to influence the residents’ sanitation conditions. The occupations and monthly incomes of residents of Belakang Padang Island and Labu Island differed substantially (Table 3). Belakang Padang Island residents participated in more varied occupations, whereas the majority of Labu Island residents were fishermen/women. They usually work at night and their income is uncertain, as poor weather prevents them from working. On both islands, most married women become homemakers, and depend on their husbands’ income. Despite differences in occupations, the residents of the two islands had similar monthly incomes, between IDR 1,000,000 and IDR 3,500,000; this range falls below the minimum standard for Batam City in 2023, which is around IDR 4,500,440 [36]. As a reference, the minimum standard salary is IDR 2,713,672 per month on Bali Island and approximately IDR 2,361,231 per month on Lombok and the Gili Islands [37, 38].
Clean water and sanitation.
The sources of clean water differed between Belakang Padang Island and Labu Island (Table 4). On Belakang Padang Island, residents accessed clean water from the SWRO facility and reservoirs, as well as community wells and household rainwater tanks (Fig 5). The residents of Labu Island relied solely on SWRO water; well water is too saline for drinking. In terms of sanitation, most residents of both islands lack septic tanks because the houses surveyed were located in coastal areas. Rather, these communities rely on tidal water to clean up discarded waste and unclean water.
SWRO facility conditions.
The SWRO facilities differ between the two islands in terms of size, energy source, clean water production, and operating time. Table 5 summarizes the results of the interviews and field surveys on Belakang Padang Island and Labu Island.
Discussion
Historically, Before Batam City was established as the site of the local government, Belakang Padang Island hosted the local government. Several government offices and other facilities remain, which attract local and foreign tourists. Because of that, there are a significant number of inhabitants on that island. Meanwhile, Labu Island is a smaller island (approximately 12.3 times smaller), with few inhabitants (around 240 times less than Belakang Padang Island). The Indonesian government has been working to meet the drinking water needs of residents on small islands, particularly during the dry season, for example through the construction of reservoirs, water tanks, and SWRO facilities. Initially, the government of Belakang Padang Island considered alternatives, including an undersea pipeline to supply clean water from Batam City; however, this strategy may disturb global shipping traffic [39]. Consequently, the government constructed SWRO facilities on Belakang Padang Island in 2016, which began operation in 2017. The initial purpose of the SWRO facilities was to provide clean water to households not connected to the reservoir pipeline system. However, due to increasing demand, more households have been connected to the SWRO facilities, ensuring a sustainable clean water supply for the inhabitants.
On Labu Island, the community endured decades of hardship due to the difficulty in accessing clean water. Inhabitants requested a solution from the government; [40] in response, the SWRO facility was constructed in 2021 and began operation in 2022. According to our 2023 interview with the water resource manager, Labu Island is too small for a reservoir, and wells were not a viable solution because the groundwater is not considered clean by the inhabitants. The SWRO facility has greatly benefited the residents of Labu Island. Notably, most workers are fishermen and women who work at night and now feel secure leaving their families, knowing they have access to clean water.
Potential obstacles include, first, the economic situation of the inhabitants. Our questionnaire revealed that more than 60% of residents had incomes below the minimum standard salary for Batam City. SWRO facilities are expensive to operate and maintain, which makes SWRO water costly [41]. However, the central government subsidizes 50% of the cost, ensuring that it remains affordable. Second, we found that most coastal residents had poor sanitation conditions due to the lack of septic tanks, which increases the risk of contaminating groundwater and pipe networks (reservoirs and SWRO) during high tides, as well as the seawater used as raw water for the SWRO system. Drinking water may be contaminated not only by sewage but also by seawater intrusion during tidal events.
However, the SWRO facility on Belakang Padang Island has experienced operational difficulties, primarily due to the failure of the high-pressure pump. According to an interview with the water resource manager, these issues were caused by an unstable electricity supply and prolonged operational hours. The SWRO facility on Belakang Padang Island has a larger capacity and operates 24 hours per day, compared to the SWRO facility on Labu Island, which is smaller and operates only 4 hours per day [42]. Furthermore, the energy for operating the SWRO facility on Belakang Padang Island is supplied by the government electric company. In contrast, the SWRO facility on Labu Island uses a diesel generator, as Labu Island does not have a central electricity source; instead, Labu Island residents rely on individual diesel generators and solar panels to meet their daily electricity needs [43].
The unstable electricity supply on Belakang Padang Island may disrupt operations, straining the machinery and necessitating more frequent repairs. Additionally, the high operational times could be a result of overcapacity. According to our 2023 interview with the water resource manager, the daily water production by the SWRO facility on Belakang Padang Island has been impacted by an increase in the number of houses connected by pipelines. The clean water generated by the SWRO facility can supply 400–500 households; however, 852 households were connected to the facility, exceeding its capacity. To address this issue, water is supplied to each household for only 10 hours per day.
The water resources manager has attempted to solve this problem by proposing repairs to the central government, but the response has been slow, and there has been a lack of funding. Additionally, replacement parts must be shipped from overseas, leading to long wait times. According to our 2023 interview with the water resources manager, during these waiting periods, residents’ water supply is maintained by drawing water from the Sekanak Reservoir and treating it with coagulation and ultrafiltration processes.
Based on the cases in the two study areas, several key points need to be addressed. In the short term, the bureaucracy surrounding SWRO facility repairs should be streamlined. The SWRO facility on Belakang Padang Island is developed, operated, and maintained by the central government (Ministry of Public Works and Housing). To initiate repairs, local managers must submit a proposal to the central government in Jakarta, which can take considerable time to be approved and funded. Meanwhile, the SWRO facility on Labu Island has not encountered any issues due to its recent development, stable electricity supply, and low workload. However, if problems arise in the future, Labu Island could face similar challenges to those on Belakang Padang Island, which is particularly concerning given the lack of alternative water resources. For this reason, the central government should grant autonomy to the local government for the operation and maintenance of SWRO facilities. Currently, there is an ongoing process to transfer the SWRO asset from the central government to the local government (Dinas Cipta Karya dan Tata Ruang Kota Batam/Public Works—Human Settlements and Spatial Planning of Batam City).
In the medium term, ensuring that the SWRO facility operates properly is crucial. While delegating SWRO repairs to the local government could expedite the process, access to resources for repairs may still pose challenges. To prevent these issues, the SWRO facility needs to be properly operated and maintained. The SWRO failure on Belakang Padang Island has occurred before, with the primary issue being the failure of two high-pressure pumps. The central government replaced one of the pumps, but the other remained unreplaced, [31] resulting in reduced water productivity and capacity. This study suggests that the problem stems from overcapacity. To meet the needs of all inhabitants, the SWRO facility operates 24 hours per day, 7 days per week, significantly increasing the risk of machine failure compared to the SWRO facility on Labu Island, which operates only 4 hours per day, 7 days per week. One potential solution is to add a new SWRO unit to the facilities to meet the capacity requirements.
Other obstacles that may become problematic in the future also need to be addressed, such as the high cost of desalinated water and the lack of septic tanks. Further studies are necessary to find solutions to these issues. If these challenges can be anticipated and mitigated, the SWRO system should be expanded to other very small islands, particularly those around Batam Island and other islands in the Riau Islands Province. However, some islands may be too remote from the main city, making it difficult to use diesel generators for running the SWRO system due to limited access to diesel fuel. Therefore, future research should explore the availability of sustainable energy sources, such as solar or wind energy, to power SWRO systems.
Conclusion
This study explored the limitations and control measures for clean water sources on two small islands in Riau Islands Province, Indonesia, using a combination of closed-ended structured questionnaires and interviews, along with direct observations.
The government has succeeded in improving residents’ clean water access on both islands through the construction of SWRO facilities. Additionally, on both islands, the cost of SWRO water is partially subsidized by the government, ensuring that residents can afford clean water.
However, several problems need to be addressed. The first is the bureaucratic delays that hinder SWRO repairs. Second, the SWRO system must be properly operated and maintained. If these obstacles can be overcome, the implementation of this system on other very small islands can be pursued in the future. Sustainable energy sources, such as wind or solar energy, should be adopted for remote islands; however, a study should be conducted to assess their availability.
Supporting information
S1 Table. Water parameter for hygiene and sanitation standard.
The standard parameter was based on Regulation of the Minister of Health of the Republic of Indonesia Number 2 of 2023.
https://doi.org/10.1371/journal.pwat.0000241.s002
(XLSX)
S1 Fig. Houses on Belakang Padang Island.
The photograph was taken by authors.
https://doi.org/10.1371/journal.pwat.0000241.s003
(TIFF)
Acknowledgments
All authors sincerely thank Universitas Internasional Batam, BLUD UPT PAB Batam City and all participants on Belakang Padang Island and Labu Island.
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