It was estimated that 2.1 billion people had no access to safely managed drinking water services in 2017 (UNICEF and WHO, 2019). Lack of access to safe drinking water leads to adverse health conditions and inhibits productive activities (Prüss-Ustün et al., 2019). Children below the age of five suffer the most from these water-related diseases, such as diarrhea, stunting, and even mortality (GBD 2016 Diarrhoeal Diseases Collaborators, 2017).

Water, sanitation, and hygiene (WASH) interventions have been conducted intensively in LMICs. Such interventions have included household water treatment (HWT), i.e., treating water oneself within a household, and includes technologies such as boiling, solar disinfection, adding chlorine, or water filtration (Sobsey et al., 2008). HWT has been effective in reducing water-related diseases in LMICs, for example, in studies conducted in Ethiopia (Mengistie et al., 2013) and Bangladesh (Pickering et al., 2019). However, previous studies have found that, in spite of its success, many households in LMICs have not extensively adopted HWT technologies or practiced it regularly (Geremew and Damtew, 2020). This can reduce the positive health effect of HWT (Enger et al., 2013).

Understanding the reasons behind adoption of HWT is essential in order to develop better WASH intervention strategies that sustain appropriate WASH behavior. RANAS, which stands for Risk, Attitude, Norm, Ability, and Self-regulation, is one of the psychological frameworks that has been used to understand the behavioral determinants of diverse water use practices (Mosler, 2012). It has been successful in explaining the use of HWT in developing countries such as Bangladesh (Inauen et al., 2013), Chad (Lilje et al., 2015), and Ethiopia (Sonego et al., 2013).

However, only few HWT studies have included and analyzed behavioral determinants, i.e., SEC and psychological factors (Fiebelkorn et al., 2012), which limits the understanding of such behavior. Dreibelbis et al. (2013) argue that combining the socio-economic characteristics (SECs) and psychological factors can even provide better systems-level understanding of WASH-related behavior. However, Lilje and Mosler (2017) argue that SEC is “less important” to measure because SEC explains only a small portion of the behavior and it is nested within psychological factors. Other WASH studies have similarly suggested that the strength of the influence of SEC is much smaller than psychological factors, once it is combined with psychological factors as independent variables at the same level of regression analysis. See, for e.g., Stocker and Mosler (2015) in the context of cleaning of water storage and Seimetz et al. (2016) in the context of handwashing behavior.

However, Daniel et al. (2020b) tested the hypothesis that the use of HWT is influenced by the household's SEC via psychological factors and the psychological factors are influenced by the household's SEC. The authors used mediation analysis and found statistically significant evidence for the hypothesis that the influence of SEC on HWT adoption is mediated by psychological variables, meaning that SEC and psychological factors could not be analyzed at the same level. A previous study has introduced and implemented this hierarchical causal framework using a Bayesian Belief Network (BBN) and combined SEC and psychological factors to analyze the use of HWT in Nepal (Daniel et al., 2019). RANAS psychological framework guided the analysis. However, RANAS factors have not completely been utilized, potential bias of self-reported answers existed, and limited SECs were used. The study presented in this manuscript therefore tackles the limitations in the previous work (Daniel et al., 2019). In addition, a BBN model with more SEC and a complete set of RANAS psychological factors was developed and constructed. No other study [other than Daniel et al. (2019)] has explored the influence of SEC on psychological factors in HWT or WASH context, i.e., such possible causal relationship has been ignored; see, for e.g., Stocker and Mosler (2015) and Seimetz et al. (2016).

The current study takes up the abovementioned hierarchical causal framework to understand the complex interlinkages between SEC and psychological factors behind the practice of HWT in a rural area in East Sumba, Indonesia. This approach not only is able to understand the complex system behind the practice of HWT but also potentially enables local stakeholders to design relevant interventions considering the household's psychological and SEC to facilitate behavioral change.

A cross-sectional study was conducted on August 3–16, 2018, in the district of East Sumba, Province Nusa Tenggara Timur, Indonesia. More than 10% of the total population in the district still follow an indigenous belief, known as “Marapu,” i.e., worship the forefathers (Fowler, 2003; Vel and Makambombu, 2019). Even though only a small portion of the population still officially practice Marapu, there is still a large influence of Marapu on the culture and daily life of the Sumbanese people (Vel and Makambombu, 2010). This area is known to be one of the poorest in Indonesia, where open defecation is common, and the prevalence of malnutrition among children is one of the highest in Indonesia (Picauly and Toy, 2013; Sungkar et al., 2015). The majority of the households used wells (44%) and surface water (spring or river) (32%) as their main drinking water sources (BPS Statistics of East Sumba Regency, 2018). This situation emphasizes the need to practice HWT regularly. However, local NGOs suggested that many of the households in this area still drink untreated water.

We targeted a number of household based on the methodology of Krejcie and Morgan (1970) and Wilson Van Voorhis and Morgan (2007) (see the Supplementary Material for more information). A total of 377 households were randomly visited during transect walk within nine villages and enrollment of every, for example, five houses (Figure 1). There were no exclusion criteria for the participation of households because we aimed to get overall situations in that area. A structured household interview contains the household's socio-demographic information, WASH knowledge and perceptions, and observations by hired local enumerators. The observation covered several hygiene indicators, such as conditions of the toilet and cleanliness of the house. The SECs were encoded in categorical variables, while most of the answers related to psychological factor questions were measured in a five-point Likert scale. The interview targeted a mother as a respondent on behalf of the household, wherever possible, because they are mainly responsible for the water management in the house. The Open Data Kit (ODK) platform on a smartphone was used for the interview and the data were transferred to the computer for analysis. The interviews were conducted in Bahasa Indonesia by six local enumerators. The survey results were checked daily, and if there was a doubt on the data, we confirmed it directly with the enumerator. The Human Research Ethics Committee of Delft University of Technology and the Agency for Promotion, Investment and One-Stop Licensing Service at the province (East Nusa Tenggara) and district (East Sumba) level approved the study setting. Participation was voluntary, and written informed consents were obtained from all respondents; as well as the consent from the village's head prior to the data collection. No household visited declined to participate in the study.

Most of the respondents (84%) were the mother, and the rest were the household head. In terms of schooling, 33% of the respondents attended at least secondary school, while only 29% among the household's head (male). The majority of the respondents (87%) had non-permanent housing walls, i.e., wood or bamboo; 7.4% a non-permanent roof, i.e., straw; and 69% a non-permanent floor, i.e., compacted soil. Twenty-six percent of the respondents followed the indigenous belief “Marapu.” Around half of the respondents mentioned that they almost never watched TV (56%). Fifty-two percent of respondents were categorized as living in relatively difficult market access.

Additionally, 29% of the respondents said that they still practiced open defecation, while 50% of the respondents had their own toilet. Thirty-four percent of the respondents had access to a piped water scheme, while 58% still relied on river or well, and 8% bought water from commercial entities or private persons, e.g., water truck or refill water station. Fifty-one percent of the respondents had a water source nearby or in the house, i.e., below 5 min per trip to get water, while 29% of the respondents needed at least 15 min per trip to fetch water. A total of 101 respondents (27%) claimed that almost all of their drinking water was treated, i.e., self-reported answer. However, after using PCA to create the variable HWT practice, 51% of the respondents were categorized as “regularly” practicing HWT, 26% as irregular user, and 23% as non-users. Moreover, 85% of the respondents answered boiling as the HWT method that they often practiced. Very few households used another type of HWT, e.g., commercial water filter (five households), which is because there was no promotion of other types of HWT in that area. Diarrhea incidence among children below the age of 5 was relatively high, 32% in the preceding 2 weeks at the time of visit; i.e., the data collection was conducted in the dry period. A table of descriptive statistics of the respondents can be found in the Supplementary Material.

Explaining water-related behavior, such as the practice of HWT, is very complex, particularly because there are multiple factors involved (Peters, 2014). Using a system-based approach that combines SECs and psychological factors, this study found that locally rooted belief and access to water highly influence people's perceptions (psychological factors) and thus the adoption of HWT. Moreover, using complete RANAS variables in the analyses, including more relevant SECs, and minimizing the bias from respondent's self-reported answers, the model's performance of this study was better than the one in Daniel et al. (2019), as shown by the AUC value of 0.94, and also provided better interpretations of within-system interactions resulting in more confident recommendations.

The results of the sensitivity analysis and predictive (Bayesian) inference show the same pattern. For example, a more educated mother perceived a higher level of the psychological factors, i.e., a positive correlation (Figure 4). This is in line with the findings of Figueroa and Kincaid (2010) who mentioned that a more educated mother may have a better understanding of the health risk of untreated water and could manage and plan better about the practice of HWT. In addition, since the mother is the primary adult caretaker and usually responsible for home WASH management, the new ways of thinking obtained from the promotional activities or school are probably translated into a sustained behavior and followed by other household members (Allen et al., 2018).

The effect of other individual socio-economic and psychological characteristics are also consistent with the literature. For example, easier information access may facilitate the spread of knowledge and understanding of health risks from untreated drinking water (George et al., 2016; Daniel et al., 2019). Easier access to market also stimulates more confidence in getting the resources needed to adopt HWT while wealth represents their ability to purchase the resources (Opryszko et al., 2010; Roma et al., 2014). This suggests that “context matters” and that SECs of households play an important role in context of health-related behavior (Manstead, 2018), e.g., in the case of women's sanitation use in Africa (Winter et al., 2018). This paper argues that including SECs is essential in order to implement a system thinking approach (Dreibelbis et al., 2013) to interpret the behavior or investigate “the causes of the causes” (Braveman and Gottlieb, 2002). Since the results show that better SECs lead to regular practice of HWT, reducing disparities in SECs is essential for healthier behavior (Adler and Newman, 2002). The similar interpretation may apply to the context of technology adoption among people in developing countries.

Indigenous belief played a significant role in this study. The analysis found it to be negatively correlated with both psychological factors of households and the HWT behavior. However, how indigenous belief “Marapu” influences the psychological factors of the people is not well-understood and should be investigated in future studies. Some WASH-related behavioral studies have also highlighted that indigenous belief plays a critical role. For example, rainwater is considered to be blessed by God and therefore HWT is perceived not to be needed in some areas of Kenya (Harris, 2005). Water from rivers such as River Ganga is considered pure by religious people in India for the same reason and often consumed without treatment (Kley and Reijerkerk, 2009). Being a Christian or not has been found to be a significant predictor of using private latrine (Winter et al., 2018). In addition, indigenous belief has facilitated a high sanitation coverage in Uganda (Okurut et al., 2015) but has led to distrust in filtered water in Bangladesh (Johnston et al., 2010). Other studies have also mentioned indigenous belief as important drivers of HWT practice in Pakistan (Mahmood et al., 2011) and Nepal (Rainey and Harding, 2005).

By understanding more about the role of belief, behavioral change interventions could be better designed, without changing their unique cultural belief and practices. For example, religious leaders could be involved in the WASH promotion activities (Dwipayanti et al., 2019). This might also work in East Sumba since the religious leader is highly influential there.

Households who need more time to collect water perceived lower levels of ability and self-regulation to operate HWT technologies. That is probably because the time to treat water, e.g., to boil and cool water (Clasen T. et al., 2008), competes with the time needed to fetch water. This issue is particularly important in East Sumba where the area faces serious drought throughout the year (Messakh et al., 2018). This finding underlines the need for easier access to the water supply to facilitate a behavioral change toward the adoption of HWT, especially because ability and self-regulation are the main two factors that related to the continuation of the behavior (Mosler, 2012).

From the BBN sensitivity analysis, the psychological factor attitude of households toward HWT was found to be the most influential variable (Figure 6). In addition, psychological sub-factor affective belief (taste), i.e., one of attitude sub-factors, was the most influential variable in the regression analysis. This suggests that if households in the area like the taste (or temperature) of the treated water, they are highly likely to regularly practice HWT. This finding could be related to another study in Pakistan where households preferred to have fresh and cold water in hot weather (Luby et al., 2001). A similar interpretation may apply to Sumba since this island is a quite hot and humid area; i.e., people prefer to have raw fresh water taken directly from tap, river, or well. Moreover, since the perception of risk appears as the second important psychological factor in BBN, highlighting the poor water quality of the fresh—but untreated—water is one of the important focuses to change the behavior. However, extra effort would be needed to ensure that households perceive treated water more positively, e.g., by finding opportunities where households experience the taste (freshness) of treated water. Boiling, which is common in the Sumba area, will release the dissolved oxygen in the water and make the water taste less fresh and thus may not be the preferred option. Therefore, other treatment systems, such as SODIS, could be a preferred option since it does not change the taste of water (Luzi et al., 2016).

There are some limitations to the presented study. First, 16% of the respondents were not the mother, i.e., the one responsible for the water management in the house. However, the means of five psychological factors and HWT practice were not significantly different (p > 0.05). Second, we only assessed the HWT practice in this study and not the safe storage practice. Safe storage is needed to prevent recontamination of treated water (Mintz et al., 1995), and, indeed, in another study in the same area, it was found that there is a “moderate” chance of recontamination due to inappropriate water storage (Daniel et al., 2020a). This implies that even though households were categorized as regularly practicing HWT in this study, the drinking water quality may not be safe to drink. Therefore, we recommend that promotion of HWT in that area must be accompanied by promotion of safe storage and hygienic conditions in the household. Future HWT studies in that area have also to include the assessment of safe storage practice in addition to the HWT practice. Third, we did not measure and include the organoleptic aspects of the water (smell, color, taste, and turbidity) in the analysis. These aspects were found to influence the perception of water quality (Doria et al., 2009) and thus should be analyzed further in the study area. Fourth, to the best of our knowledge, there is no practical method to confirm the actual practice of boiling, such as measuring the residual chlorine or observing the presence of bottles in the case of chlorination and solar disinfection, respectively. Therefore, a potential of self-reported bias in our study exists, even though we tried to minimize it by combining multiple answers. A previous study in Cambodia found that only one-third of the self-reported households had boiled water at follow-up visits (Brown and Sobsey, 2012). In addition, other studies found that boiling does not fully eliminate the water contamination (Clasen T. et al., 2008; Clasen T. F. et al., 2008). A future study should also analyze the effectiveness of boiling practice in this area.

In this study, the role of SECs of people in the indigenous Sumba area in Indonesia on the water-related perceptions and the practice of HWT were analyzed. Statistical analyses were combined with BBN models to accomplish this. It was found that SECs influenced water-related perceptions (psychological factors), resulting in higher or lower adoption of HWT. Indigenous beliefs played a significant role in influencing household perceptions, suggesting the importance of considering local culture in the dissemination of health- or environmental-related advisories and adoption of relevant technologies in developing countries. Access to water was found to be important for households to develop the ability to practice HWT. For improved adoption of HWT, attitude toward the HWT, especially the taste of treated water, also needs to be addressed to influence households to practice HWT. Finally, this paper argues that improving the aforementioned SECs of the respondents is essential to ensure the sustainable use of HWT or any environmental-related technologies in developing countries.

The original contributions presented in the study are included in the article/Supplementary Materials, further inquiries can be directed to the corresponding author/s.

The studies involving human participants were reviewed and approved by the Human Research Ethics Committee of Delft University of Technology and the Agency for Promotion, Investment, and One-Stop Licensing Service at the province (East Nusa Tenggara) and district (East Sumba) level. The patients/participants provided their written informed consent to participate in this study.

DD: term, methodology, software, formal analysis, investigation, resources, writing—original draft, writing—review & editing, visualization, and funding acquisition. SP: term, conceptualization, methodology, validation, writing—review & editing, supervision, and project administration. LR: term, conceptualization, validation, writing—review & editing, supervision, project administration, and funding acquisition. All authors have read and agreed to the published version of the manuscript.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.