How does the citizens' choice of water use actions based on their empirical knowledge affect the water quality in a rural community of the Philippines?

In developing countries, the water, sanitation and hygiene (WASH) environment is of the utmost concern, particularly in terms of community development and education. Frequent reports have emphasized that access to the WASH environment is strongly related to childhood growth and development, and school performance. In particular, the stunting of babies and children is among the most serious WASH-related issues, due to the WASH conditions being directly related to access to safe and stable water and food (Ngure et al. 2014; Cumming & Cairncross 2016; Hutton & Chase 2016; Mbuya & Humphrey 2016; Pickering et al. 2019). Furthermore, the economic impacts of inadequate WASH environments are significant. Improving WASH conditions could help maintain healthier working-age populations and ultimately reduce poverty, thereby saving younger generations (Cumming & Cairncross 2016; Hutton & Chase 2016).

The country of the Philippines, including the target rural community of this research, is no exception. Health issues induced by microbial contamination, stemming from the lack of a WASH environment, remain common wherever water is used by local citizens (Capuno & Tan 2015). Several studies have shown that microbial contamination in daily water sources such as refilling stations, district water pipes, and deep wells remains prevalent, particularly after disasters and heavy rains (Ventura et al. 2015; Rebato et al. 2019; Yazawa et al. 2024). Factors contributing to microbial contamination include unsanitary toilets, improper garbage disposal, animal waste, and untreated wastewater (Capuno & Tan 2015).

For people who live in the rural provinces of the Philippines, daily water resources are highly dependent on groundwater (Capuno & Tan 2015; Yazawa et al. 2024). However, the management of sustainable water resources is significantly inadequate, with challenges including unsustainable water extraction, population growth (i.e. increased water demand), urbanization, and water pollution being caused by untreated wastewater (Tayone 2015; Hutton & Chase 2016). Furthermore, households in rural areas have no access to piped water or sanitation facilities, i.e. the WASH environments (Capuno & Tan 2015; Pfadenhauer & Rehfuess 2015; Ignacio et al. 2018; Vally et al. 2019; Alipio 2021).

Underlying these challenges are various management issues, stemming from both the difficulty in implementing regulations and the lack of monitoring facilities. For example, in some areas, water refilling stations do not have sanitary permits (Rebato et al. 2019), although people trust that the sterilized water they buy from water refilling stations is safe (Onabia et al. 2023). In addition, the water quality at the household level or point of use is not monitored unless a specific incident occurs, such as an outbreak in a community (Capuno & Tan 2015). Water quality testing is not easy to implement in the rural areas of the Philippines because of its transportation and labor costs (Alipio 2021; Yazawa et al. 2024). Thus, regular water quality inspections are seldom conducted. Consequently, people rely on their own knowledge of water use and its quality management, often applying disinfectants based on past practices rather than precise calculations (Ventura et al. 2015).

Improving access to the WASH environment and enhancement of WASH practice/education, which currently reflects the local people's empirical knowledge, is crucial to improve sanitary conditions in provinces of the Philippines. However, local citizens' empirical knowledge of water quality usage and management in provinces of the Philippines has not yet been verified because of the lack of basic water quality information. Thus, this research sought to verify the hypothesis that local people's water use actions – based on their empirical knowledge – are not necessarily safe. This research employed the first comprehensive citizen-scientific investigation, collecting both quantitative data and qualitative information, with local citizens through direct observation and discussion with individual houseowners in a rural community in the Philippines. The specific objectives were (1) to assess the water quality based on the purpose of water consumption in households in the municipality of Barbaza, the Province of Antique, Philippines as a case study area; and (2) to examine the effects of their actions on the quality of the water they use, through a descriptive study.

The novelty of this research lies in obtaining the water quality data via citizen-scientific investigation and in using these data to discuss the water quality situation in each household with owners on the spot. The water quality data were obtained and recorded in cooperation with local citizens using simple multi-water quality meters and smartphones. This research demonstrates that water quality data can be a catalyst of communication for local people to understand the importance of maintaining adequate WASH environments by directly sharing the water quality data and their meanings with them. According to the local clinic doctor in the municipality, measures are currently taken only after an outbreak of cases. However, by teaching local citizens how to deal with water pollution by themselves, this research could contribute to effective preventive measures in the future. Although the research was conducted in one community with limited household samples, the methodology and findings of this research will be further applied to other communities by local water management governors, practitioners, and citizens, particularly in Southeast Asia, where strong relationships exist among the people within communities.

This research was conducted with the support of households in the municipality of Barbaza, the Province of Antique, Philippines. The Province of Antique is located in the western region of Panay Island, Western Visayas. With a population of more than 23,000, based on the 2020 census, the municipality of Barbaza is situated in the middle of the province (Philippine Statistics Authority, 2021). Water samplings and household interviews were supported by the local citizens in the Barangay Binangbang Centro under the observation of the Barangay officers or representatives and with official permission from the Barangay captain.

The households supporting this research were selected based on the owners' availability, willingness to obtain the results, and consent to the findings being published. In total, 20 households in the Barangay cooperated in this research. The authors visited each house in turn and collected water samples. The water sampling and interviews were conducted by visiting the Barangay several times from February 10 to 18 and from March 12 to 23, 2024. The purpose of the interview was to identify the ways in which households differentiated their methods of water use, depending on different purposes. Based on interviews and discussions, the following three basic types of water samples were collected and analyzed, according to the purpose of water consumption: drinking water, tap water, and well water. In this research, drinking water is defined as the water drunk by local people, regardless of its source. It includes water bought from local water filling stations and/or tap water and well water that is used by each household for the purpose of drinking. For tap water or well water that was drunk directly, i.e. without treatment, the water sample was categorized as such, rather than being considered as drinking water.

During the water sampling, any basic water usage conditions and special water use actions taken by the local people were also identified through interviews; for example, an empirical device for safely using water. Although this research did not conduct a paper-based questionnaire survey, we asked citizens where they get water (i.e. sources such as well, tap, and water refilling stations) and how they treat the water depending on purposes, such as cooking, dishwashing, showering, and drinking through communication with them. In households that implemented a special water use action, water samples were collected both before and after implementing the device. For example, if a self-made filter was installed on a storage pump for a well, water samples would be obtained from a well with a filter and from the same well after removing the filter. If well water was stored in a bucket inside a household, two water samples were collected, including the original well water and the stored water in the bucket. A comparison of the water quality of these water samples, both before and after a certain action was implemented, was conducted to investigate the effects of local people's water use actions on the quality of the water they used. Based on the water quality results, this research conducted a descriptive discussion.

In this research, water quality was assessed by comparison with the two national water quality guidelines: the Philippine National Standards for Drinking Water of 2017 (hereafter PNSDW) (Department of Health 2017) and the Water Quality Guidelines and General Effluent Standards of 2016 (hereafter WQG-GES) (Department of Environment & Natural Resources 2016), depending on the target parameters. As a stricter standard, the PNSDW, was primarily used for the water quality assessment because this research focused on the water used for daily consumption by the local people, with the WQG-GES being referenced for certain parameters that are unavailable in the PNSDW.

Table 1 depicts the water quality standards and the information sources employed in this research. The water quality analysis conducted in this research focused on the following six parameters for all water samples: temperature; pH; electrical conductivity (EC); total dissolved solids (TDS); E. coli; and coliform. In addition, Ammonium-nitrogen (NH₄-N), Nitrite-nitrogen (NO₂-N), and Nitrate-nitrogen (NO₃-N) were measured for well water samples since high nitrogen concentration in groundwater implies the impacts of anthropogenic or non-point sources, such as septic tanks and livestock farms (Sahoo et al. 2016; Yazawa et al. 2024). However, the water quality standard for NO₂-N concentration was unavailable from either the PNSDW or the WQG-GES. Thus, the discussion was mainly based on the NH₄-N and NO₃-N concentrations in this paper.

The PNSDW handles three methods of E. coli and coliform analysis: the multiple tube fermentation technique (MTFT); the enzyme-substrate coliform test (EST); and the membrane filter technique (MFT). This research employed the standard values of the MFT for water quality assessment with consideration of its methodology using a similar agar (Ukpong & Udechukwu 2015). Standard values of water temperature and EC were unavailable from either the PNSDW or the WQG-GES. It is known that a water temperature ranging from 20 °C to 60 °C is suitable for the microorganism's growth (Health Canada 2021). Thus, this research considered this temperature range for reference. The evaluation of EC was substituted by the evaluation of TDS since EC is correlated to TDS concentration (Yazawa et al. 2024). The PNSDW separately sets the water quality standards of pH and TDS for drinking water, as shown in Table 1. Thus, it should be noted here that the water quality assessment referred to different standard values, depending on the source of the water sample.

The measurements of pH, EC, and TDS were facilitated by the pH/EC meter (EA776AE-3A, Hanna Instruments, USA). These parameters were measured on the spot at each household and recorded by local citizens who supported the water sampling. Single-point calibration of the pH/EC meter was conducted on the first day of water sampling each month using standard solutions with a pH of 7.01 and an EC of 1413 μS/cm (Hanna Instruments, USA). The collected water samples were stored in sterile polypropylene bottles and transported to a local laboratory. The preparation of E. coli/coliform enumeration and the analysis of NH₄-N, NO₂-N, and NO₃-N were conducted within the same day. The E. coli/coliform was counted using the Petrifilm^™ Rapid E. coli/coliform Count Plates (REC plates, 3M, USA). The REC plates were first inoculated with 1 mL of water samples, using a pipette. Because of the REC plates' recommended counting range, i.e. less than 100 colonies/mL, the collected well water samples were diluted in 10- and 100-fold using 3M^™ Diluent with phosphate buffered saline (PBS, 3M, USA). This dilution process was performed in anticipation that the expected E. coli/coliform concentration of raw well water would be higher than the recommended range, based on previous groundwater quality studies conducted in the Philippines (Leopoldo et al. 2017; Jalil et al. 2022). The plates were then incubated at 35 °C of temperature for 18–24 hours.

The concentrations of NH₄-N, NO₂-N, and NO₃-N were analyzed through the SMART PACKTEST application (Kyoritsu Chemical-Check Lab., Japan), using the iPhone 12 Pro Max. The well water samples were colored in the PACKTEST polyethylene tube, which contains a reagent to measure specified water quality parameters. After a certain reaction time, designated for each water quality parameter, the water quality concentration of samples was measured by taking photographs of the colored samples and using the Standard Color sheet (Yazawa et al. 2024). Following this procedure, the detection limit of the nitrogen parameters is designated as 0.2–5 mg/L for NH₄-N, 0.005–0.2 mg/L for NO₂-N, and 0.2–2 mg/L for NO₃-N in the SMART PACKTEST application.

The spatial distribution of NH₄-N, NO₂-N, and NO₃-N concentrations in a community was investigated using GIS. The locations of wells from which water samples were collected in February and March were separately plotted on a map using the ArcGIS 10.8 software, based on the longitude and latitude obtained from a smartphone. The high-resolution population density map (Tiecke et al. 2017) for 2022 (Data for Good at Meta, Philippines: High Resolution Population Density Maps + Demographic Estimates) was then overlaid to check the household density in the community. This research assumed that wastewater affects the spatial distribution of nitrogen concentrations in wells since wastewater treatment is still under development in this area. Population density was used as a parameter to represent the household density and the amount of wastewater.

One drinking water sample was obtained from a gallon container connected to a water dispenser to cool/heat the water, while other drinking water gallons/bottles were stored at room temperature. For drinking water, 45.0% of drinking water samples were found to be outside of the standard pH range and 35.0% of drinking water samples exceeded the TDS standard. Only 15.0% and 25.0% of drinking water samples met the standards of pH and TDS. Although E. coli was not detected in any drinking water samples, the presence of coliform was confirmed in 85.0% of them. Since the average temperature of drinking water was 28.3 °C, the storage conditions of drinking water could be contributing to increased TDS and coliform concentrations.

With regard to tap water and well water, all of the samples tested – excluding those for which data were unavailable (five samples for tap water and four samples for well water) – were found to be within the standard pH range and below the standard of TDS. However, the presence of E. coli was confirmed in 14.3% of tap water samples and 20.7% of well water samples. Coliform was also detected in the majority of tap water (85.7%) and well water samples (67.2%). Tap water, the source of which is pumped groundwater, and well water are widely used in the community for various purposes, including handwashing, bathing, laundry, dishwashing, and drinking in some cases. As a result of the water quality assessment, it was revealed that the water sources that are frequently accessed by local people, including children, are highly polluted by microorganisms.

As previously mentioned, the water in wells where NH₄-N was detected already exceeded the WQG-GES standard. NH₄-N was detected throughout the area, although there was no spatial feature of its distribution and correlation with population density in either month [Figure 3 (a) and (b)]. There were four wells in February and three wells in March with NO₂-N. Similarly, the detected NO₂-N did not have a spatial feature and correlation with population density. A relatively high concentration of NO₃-N was confirmed in the higher elevation area near the main road, although the results were below the standard.

The effects of these water use actions on the quality of the water used by local people was investigated, based on the changes in E. coli and coliform concentrations. Regarding the effects of using a plastic pipe [Figure 4(a) and Table 3(a)], the concentrations of E. coli and coliform without a pipe were 0–6 CFU/mL and 40–115 CFU/mL, respectively, while the E. coli and coliform concentrations with a pipe were 0–10 CFU/mL and 0–109 CFU/mL, respectively. This indicates that using a plastic pipe as an outlet for a well pump does not necessarily affect the quality of the water they use.

With regard to using old clothes as a filter at an outlet of a well pump [Figure 4(b) and Table 3(b)], the coliform concentration was increased, from 0 to 10 CFU/mL to 0-TNTC (too numerous to count), when using the clothes as a filter. Although E. coli was not detected in the water samples collected on this occasion, there would be a high risk of local people being exposed to the microorganisms. Storing well water in a bucket [Figure 4(c) and Table 3(c)] resulted in drastic increases in both E. coli and coliform concentrations. In the original well water, no E. coli was detected and coliform at 3–90 CFU/mL was observed. Once the well water was brought to the house and stored in a bucket, both E. coli and coliform concentrations were increased up to the TNTC level, which is more than 100 CFU/mL.

Throughout the field investigation and interviews in the community, it was observed that people in rural communities differentiated their use of water sources, depending on the purpose. The selection of water sources and several water use actions were based on their traditions and empirical knowledge. In this research, the analyses investigated the water quality conditions of the three main water types – drinking water, tap water, and well water – used by people in the rural areas of the Philippines. Furthermore, this research focused on the three typical actions that have traditionally been taken by local people; that is, using a plastic pipe as an outlet for a well pump, using old clothes as a filter, and storing well water in a bucket for daily usage. The associated changes in water quality were then examined.

In the PSNDW, stricter water quality standards are set exclusively for drinking water. Among the tested drinking water, which local people commonly believe to be safe, many of the sample measurements were found to be outside of the pH standard range and exceeding the TDS standard value. If a container is made of metals, such as copper or aluminum, the container itself and the storage duration would affect the TDS concentration (Packiyam et al. 2016). However, the households used plastic containers in the target area. The results implied that the TDS concentration was caused by contamination from the outside, such as dust or contaminants from a dipper or a hand.

The coliform group was also detected in the drinking water samples stored at room temperature, i.e. favorable temperatures for the microorganisms' growth, implying that users are at risk of ingesting microorganisms from the water they drink. Local people usually buy water from the local water-filling stations and unquestioningly believe that this is the safest source. The material of water storage containers also matters for an increase in the coliform concentration (Packiyam et al. 2016). A plastic container does not have antimicrobial properties. It would cause the formation of biofilm layers and an increase in the coliform concentration (Mellor et al. 2013). Furthermore, long storage duration at room temperature and no/low residual chlorine conditions would promote bacterial growth, as Packiyam et al. (2016) and Gonzalez et al. (2020) reported based on their experiments. The results of the water quality assessment in this research suggest that some preventive measures need to be taken, even when drinking water that has been paid for, such as cooling water when stored and heating/boiling water before using it.

The presence of E. coli, which is a fecal coliform, and coliform was confirmed in both tap and well water samples. These water sources are frequently accessed/touched by local children, implying that there are facing health risks such as diarrhea and malnutrition. Currently, water quality data at the point of use are not usually available unless there is an issue, such as an outbreak, mainly due to financial restrictions, transportation and labor costs, and the lack of facilities (Capuno & Tan 2015; Alipio 2021; Yazawa et al. 2024). Thus, the implementation of strict regular monitoring should be encouraged, following the national regulation of local water-filling stations and wells, which are the main sources of drinking and tap water within communities.

Changes in water quality associated with the empirical/traditional actions taken by local people were investigated in this research, as shown in Figure 4. Among the three types of typical water use actions, only using a plastic pipe as an outlet for a well pump did not affect the water quality [Figure 4(a)]. In contrast, the other two actions—using old clothes as a filter at the outlet of a well pump and storing well water in a bucket inside the house—drastically increased the concentrations of E. coli and coliform [Figures 4(b) and (c)]. Citizens install a plastic pipe at an outlet just for the ease of water collection. The aerugo is occasionally observed if a pipe has not been replaced for a long time. Although the aerugo itself is not a major pollutant and thus putting a pipe might not affect the water quality on the spot, poor management of a plastic pipe might cause biofilm formation and affect water quality conditions such as copper ions and algae growth.

This research focused mainly on E. coli and coliform to investigate the impacts of people's empirical water use actions on water quality. However, solely using E. coli and coliform as indicators for the assessment of the WASH environment does not account for all environmental/health risks caused by other pathogens, chemical, and physical parameters. In a rural community, however, E. coli and coliform are often the prioritized indicators to be checked for the assessment because they are used worldwide in water quality guidelines and some standard testing methods could be applied to the environment in a developing region. Thus, it should be noted that the existence of other pathogens, such as viruses, protozoa, and parasites, as well as chemical and physical parameters also need to be checked for an in-depth and comprehensive biological risk assessment to prevent outbreaks.

Putting disinfectants might be the best way since no chlorination has been conducted so far in the community. However, it is difficult for the community to frequently implement it because of the availability of disinfectants and the lack of people who can manage such as doctors. Thus, this research suggests boiling water before drinking and cooking, washing a bucket and dipper before refilling, washing hands with soap before using a dipper, and using a narrow-neck container as examples of feasible methods in the Barangay Binangbang Centro based on some experiments conducted by Mellor et al. (2013) and Packiyam et al. (2016).

The citizen-scientific investigation, conducted in collaboration with local citizens, enabled us to collect both quantitative data (i.e. water quality values) and qualitative information (i.e. empirical/traditional water use knowledge of local people). Furthermore, the methodology of water quality assessment using only portable equipment allowed us to gather data that could be used on the spot for discussion with houseowners. Local people have specific concerns about the water they use. For example, they had several inquiries about the distance between a well and a septic tank, temporary methods to treat the water themselves, and preventive measures they could take as a community. Thus, the methodology used in this research can help to address the specific issues that are concerning local people. Moreover, it can contribute not only to the water quality assessment in the community but also to citizen-led WASH environmental management in the rural areas of the Philippines.

This research performed a water quality assessment based on the purpose of water consumption among households in the municipality of Barbaza, the Province of Antique, Philippines, following the national water quality guidelines. Then, the effects of the empirical/traditional water use actions of local people on the quality of the water they use was investigated through a descriptive study using water quality values. Most of the drinking water in the community did not meet the standards of pH, TDS, or coliform. Tap water and well water samples mostly met the standards of pH and TDS. However, E. coli and coliform were detected and nitrogen pollution in well water was confirmed.

Several implications arise from the results of the water quality assessment. For example, local people usually buy water or treat water by themselves and believe the water is safe. However, the tested drinking water was partially polluted, as some of the samples contained coliform. Local people use old clothes as a well pump filter. This practice actually increased the coliform concentration from 0 to 10 CFU/mL to 0-TNTC (TNTC indicates more than 100 CFU/mL in this research). Storing well water in a bucket at room temperature was also a common practice among local households. Disinfection is not usually conducted after water collection and before consumption in the community. This practice increased both E. coli and coliform concentrations up to the TNTC level. Throughout these investigations, it was revealed that some of the empirical/traditional water use actions taken by local people negatively affect the quality of the water they use for daily purposes. In particular, there is a high risk that local people will be exposed to microorganisms.

This research suggested boiling water before drinking and cooking, washing a bucket and dipper before refilling, washing hands with soap before using a dipper, and using a narrow-neck container as examples of feasible methods in the target research area. In this research, however, empirical water use knowledge/actions were surveyed based on the interview and descriptive study. An in-depth water quality investigation is needed in further research. Water quality data collection must be continued to enable statistical analysis to check if there are significant differences in each water use condition. For the management of the community's WASH environment, specific actions should be suggested based on the results of the water quality assessment in concomitant with the encouragement of local people's perceptions. In that sense, the citizen-scientific approach performed in this research could work as a bit of wisdom for future community studies.

We would like to thank the municipality of Barbaza and houseowners there for their approval and support to conduct this research. This research was supported by the year 2023 special fund of the Institute of Industrial Science, The University of Tokyo, JSPS KAKENHI Grant Number 24K20969, and The Obayashi Foundation Grant Number 2023-Research-15-153.

All authors contributed to the conception and design of this research. Taishi Yazawa was in charge of conceptualization, methodology, formal analysis, writing original draft, project administration, and funding acquisition. Kenn Joshua Geroy Rubite and Princess Eden Macabata-Rubite contributed to data collection, investigation, and writing – review & editing.

All relevant data are included in the paper or its Supplementary Information.

The authors declare there is no conflict.