Narrative Review of Primary Preventive Interventions against Water-Borne Diseases: Scientific Evidence of Health-EDRM in Contexts with Inadequate Safe Drinking Water

Waterborne diseases account for 1.5 million deaths a year globally, particularly affecting children in low-income households in subtropical areas. It is one of the most enduring and economically devastating biological hazards in our society today. The World Health Organization Health Emergency and Disaster Risk Management (health-EDRM) Framework highlights the importance of primary prevention against biological hazards across all levels of society. The framework encourages multi-sectoral coordination and lessons sharing for community risk resilience. A narrative review, conducted in March 2021, identified 88 English-language articles published between January 2000 and March 2021 examining water, sanitation, and hygiene primary prevention interventions against waterborne diseases in resource-poor settings. The literature identified eight main interventions implemented at personal, household and community levels. The strength of evidence, the enabling factors, barriers, co-benefits, and alternative measures were reviewed for each intervention. There is an array of evidence available across each intervention, with strong evidence supporting the effectiveness of water treatment and safe household water storage. Studies show that at personal and household levels, interventions are effective when applied together. Furthermore, water and waste management will have a compounding impact on vector-borne diseases. Mitigation against waterborne diseases require coordinated, multi-sectoral governance, such as building sanitation infrastructure and streamlined waste management. The review showed research gaps relating to evidence-based alternative interventions for resource-poor settings and showed discrepancies in definitions of various interventions amongst research institutions, creating challenges in the direct comparison of results across studies.


Introduction
Water-borne diseases (WBDs) are infectious diseases, such as cholera, shigella, typhoid, hepatitis A and E, and poliomyelitis, that are transmitted to humans through contaminated aims to reduce health risks and the onset of disease through health promotion, education, and awareness; secondary prevention aims to stop disease progression by screening and identifying infected individuals, while tertiary prevention focuses on treatment of disease [13]. Primary prevention, and interruption to reduce transmission, is the most cost-effective method in reducing the burden of infectious disease per capita in populations with poor access to healthcare [13,14]. Effective bottom-up approaches from an empowered community, along with top-down governance and policy, allow successful implementation of primary prevention and behavioral modification throughout the disaster management cycle: prevention, mitigation, preparedness, response and recovery [11][12][13]. Interventions that aim to improve access to WASH are main bottom-up approaches for reducing risks of WBD in endemic rural areas [15].
The United Nations Sustainable Development Goals 2015-2030 (SDG) aims to eradicate poverty and achieve a more sustainable future for all [16]. The alleviation of the burden of WBDs globally will have a cross-cutting impact on several SDGs [16]. This review examines the available published literature on primary preventive interventions against WBDs, the strength of evidence behind these interventions, and the feasibility or barriers of successfully applying health-EDRM approaches for WBD prevention in contexts with inadequate safe drinking water, or resource-poor settings.

Materials and Methods
A literature search on studies with interventions designed to reduce transmission of WBD was conducted.

Search Strategy
PubMed, Science Direct, Web of Science, Medline, and Scopus databases were searched in March 2021 using the MeSH key words: water, sanitation, hygiene, WASH, waterborne disease, intervention, prevention, primary prevention, measures, health-EDRM, unclean water, inadequate safe drinking water, population and community Boolean operators then combined the key words by similarity of definition into a search term: ((water AND sanitation AND hygiene) OR WASH) AND (waterborne disease) AND (intervention OR prevention OR primary prevention OR measures OR health-EDRM) AND (unclean water OR inadequate safe drinking).

Inclusion and Exclusion Criteria
The search was limited to human studies in international peer-reviewed journals, online reports and electronic books published in English. The search included any studies relating to any WBDs, with no distinction between causative agent or symptoms. Eligible studies were retrieved, and their bibliographies were checked for further relevant publications. To obtain the most relevant literature for this review, the titles and abstracts were screened against the inclusion and exclusion criteria.
English-language based article.
Effectiveness of primary prevention methods against waterborne diseases mentioned in the abstract.
Abstracts that did not mention primary prevention methods against WBD.

2.
Papers studying only foodborne and/or airborne diseases.

3.
Papers studying secondary and/or tertiary level prevention.
Full texts of potential papers were assessed and excluded if the effectiveness of the primary prevention intervention was not reported. Through a snowballing method, further texts were identified through the references of the identified publications that fit into the inclusion criteria.
The identified papers were then categorized according to the Oxford Centre for Evidence-Based Medicine (OCEBM) 2009 Levels of Evidence (Table 1) which determines the strength of evidence of a piece of research according to its study design and methodology [17]. The papers obtained from each database were collected and consolidated, and duplicates were removed. Case series (and poor-quality cohort and case control studies) 5 Expert opinion without explicit critical appraisal, or based on physiology, bench research or "first principles"

Results
The process of identifying relevant publications is outlined in Figure 1. The initial database search identified 994 search records, of which 64 were removed due to duplication. This was refined to 140 records following the screening of titles and abstracts, after which the full-texts were read and assessed for inclusion. From these results, 32 full texts were included, in addition to 56 identified through the snowballing method. The total number of studies included in this review are 88 .

Strength of Evidence of Identified Studies
Each of the 88 identified studies were assessed in strength of evidence of their studies, according to the OCEBM Levels of Evidence (Table S1) [17].
The included studies were categorized according to the type of intervention studied, which resulted in a group of eight common bottom-up, non-pharmaceutical, primary preventive interventions, based on the health-EDRM framework. These were: two "personal" protective practices (regular handwashing, intake of prophylactic supplements), four "household" practices (household water treatment, household water storage, maintain household cleanliness, household waste management) and two "community" practices (build community infrastructure, conduct community education) were identified. 13% of the studied literature was associated with personal practices, 65% with household practices and 22% with community practices. The review of evidence was disaggregated according to the eight preventive interventions, and categorized according to OCEBM Levels of Evidence [17], which can be found in Table 2.
The comparison of the strength of evidence of the reviewed literature (Table 2) showed that the largest proportion (35%) of identified publications fell into Level 1B classification, which includes randomized controlled trials with narrow confidence interval and the majority of these studies investigated the effects of water treatment for WBD prevention. Level 4 studies, including cross-sectional mixed-method studies and case series studies, accounted for 17% of the identified publications, which mainly evaluated the possible association between perceptions, WBD prevalence and preventive interventions in targeted populations with interviews, questionnaires and surveys. Among the 88 studies, no systematic review of case-control studies and only one systematic review of cohort studies was identified. Level 3B studies, including case-control studies, only accounted for 3% of the identified publications. There was more literature on preventive interventions at household levels (65%) with a significantly stronger study design, compared to interventions at community (22%) and personal levels (13%). Regarding individual primary preventive interventions, high-strength evidence is most available concerning the practice of water treatment, and lacking at different levels in practices of household waste management (6%) and household cleanliness (7%), with only one study available for chemoprophylaxis (0.6%).

Overview of Studies Included for Analysis
Tables 3-6 summarize each of the 8 primary preventive interventions against WBDs at personal, household and community levels. Without distinction by causative agent, disease symptomology, or therapy, the tables are a compilation and comparison of each preventive methods, according to their potential health risk, desired behavioral changes, potential health co-benefits, enabling and limiting factors and strength of evidence available in published literature. The tables also identify suggested alternative measures for each intervention, which are variations of the action that have the intention of achieving a similar result, but may be implemented differently, for example, if the materials or resources required to undertake the intervention are not available or accessible.  1 Of the 88 publications reviewed, some included findings on more than one prevention measure, and are counted more than once. Table 3. Personal protection practices as primary preventive interventions against WBDs: regular handwashing and intake of prophylactic supplements.

Risk
• Waterborne pathogens such as bacteria, viruses and parasites can be transmitted as one touches the eyes, nose or mouth after contacting contaminated water sources without adequate handwashing [106] • Children are at risk of parasitic infections transmitted from the household environment if their caregivers do not practice adequate handwashing [47].

•
Approximately three billion people worldwide do not practice regular handwashing due to lack of access of soap and water, with higher incidence of diarrheal diseases in such population [107] • Dehydration is the most severe threat posed by diarrheal diseases, as water and electrolytes are lost through liquid stools, vomit and sweat. This could be life-threatening in severe cases where losses of electrolytes are not replaced [2] • Zinc supplementation along with oral rehydration solution (ORS) has emerged as a potent approach in WBD management: zinc strengthens gut lining and reduces severity, whereas ORS replenishes electrolytes and rehydrates dehydrated individual [56] Behavioral Change • Handwashing, with or without soap, in clean and running water at regular intervals to reduce the risk of contracting of WBD [19,20,35,38,42,[45][46][47]60,61,68,72,73,[78][79][80]104,105] • Handwashing at vital times such as prior to food preparation and after toilet use to prevent transmission of waterborne pathogens via fecal-oral route [21,46] • Oral intake of zinc and oral rehydration salt to prevent and manage diarrheal illness by averting dehydration [56] Co-benefits • Effective in reducing number of days with diarrhea in severely malnourished children [71] • Reduces occurrence of other diseases such as respiratory infection [68,78], skin infections [68], and nutritional deficiency [47] • Effective at preventing contraction of other diseases in HIV-infected children, regardless of anti-viral regimen [45] • Visually cleaner hands [47] • Reduces antibiotics use in management of WBD [56] • Reduces WBD associated hospitalization [56] Enabling Factors • Access to clean water [19,49,60,61,80,105] • Access to soap [104] with no difference in incidence of diarrhea between households with plain soap compared to antibacterial soap [20,69,72] • Education: increase awareness of the needs and benefits of handwashing can further promote behavioral change [38,47,73,78,80] • Financial support: sufficient funding to roll out hand hygiene interventions in schools with distribution of resources [78] • Education: understanding the benefits of supplements with appropriate consumption and dosage [56] • Baseline water quality: purification sachets so prophylactic supplements can be taken with clean water to maximize effectiveness [56]

Parameters Regular Handwashing Prophylactic Supplements
Limiting Factors • Distance of facilities: decrease in hand washing behavior when sanitation facilities are placed at a further distance [35] • Ways of transmission: multiple pathways for ingestion of faecal pathogens and no significant difference has been found in the amount of ingested pathogens by children despite water, sanitation and hygiene interventions (WASH), as E. coli was still found on food [108] • Socioeconomic status: poorer households are less able to adapt hand washing behavior rapidly [61] • Unsustainable behavior: lack of health impact outside intervention period due to unsustained adaptation of behavioral change [76] • Access to prophylactic supplements [56] Alternatives for resourcepoor settings

•
Use of alcohol sanitizers • Handwashing with ash, mud, soil with or without water which could inactivate and rub away pathogens [20] • Consumption of water-rich fruits and vegetables to prevent dehydration [109] Strength of evidence • Only one study was identified that reported the association between increase in uptake of ORS and zinc supplements and lower prevalence of diarrhea [56] Table 4. Household practices as primary preventive interventions against WBDs: household water treatment and household water storage.

Risk
• Water contains many impurities and can be easily contaminated by harmful chemicals and waterborne pathogens (viruses, bacteria and parasites), which can lead to water-related diseases and other serious health issues if left untreated [7] • Diarrhea incidence is positively associated with consumption of untreated and unsafe water [26,29,83,85,90] • Boiling water is insufficient in killing all waterborne microbes and other new-age contaminants, and thus higher risks of diarrhea compared to other water treatment [29] • Risk of recontamination during the process from water collection to consumption, point-of use treatment is therefore important to maintain health benefits from improved supply [100] • Water is subject to frequent and extensive microbial contamination during collection, transport and storage, as waterborne pathogens can still enter and propagate after the point of collection [31,43]   Cultural beliefs: some communities believe that boiling water is sufficient in preventing WBD as it has been heavily promoted for decades, and are therefore reluctant to adapt other treatments [29] • Socioeconomic status: wealthy households are able to adapt water treatment behavior more quickly [61,102] • Suitable and appropriate design of storage containers: less compliance with unpopular designs, but increase in the use of storage containers with a more practical design despite lower effectiveness compared to other storage methods [43] Alternatives for resourcepoor settings

•
Point of use filtration in areas where water infrastructure facilities are not improved [25] • SODIS is adopted in low-income households as they cannot afford filters, reduction in diarrhea incidence is still observed although less compared to the use of filter [25] • Use of bleach in low-income households as they cannot afford flocculant disinfectant, reduction in diarrhea incidence is still apparent although less compared to use of disinfectant [51,60] • Bottled drinking water: similar reduction in diarrhea incidence when compared to water treatment [95] •  • Ingestion and exposure to human waste is associated with diarrhea and other WBD; interventions aimed at improving excreta disposal have found to be protective [24] • Shared sanitation facilities tend to be dirtier than private facilities, can be easily contaminated with waterborne pathogens, and are therefore associated with higher risks of moderate-to-severe diarrhea [20,47] • 17% of rural population remain without access to a toilet or latrine, which leads to practice of open defecation and unsafe faecal disposal, contributing to sustained increase of diarrhea incidence [34] • Children in households with simple pit latrine have 7 times higher odds of intestinal parasitic infection than those with water-sealed latrines [47] Behavioral Change • Neighbors: household members with improved sanitation may still be exposed to waterborne pathogens if their neighbors have no improved sanitation due to close proximity [20,34,77] • Affordability for construction: household sewer connection was associated with greater reduction in diarrhea compared to other household sanitation facilities [58] Alternatives for resourcepoor settings

•
Use water to clean instead of cleaning products • Lay low-cost earthen adobe floor to replace dirt floor [110] • Minimize the number of households that share the facilities [20,47]

Strength of evidence
• No studies mentioned ways of implementation to maintain cleanliness (e.g., use and effectiveness of cleaning products) • Strong evidence for association between improvements in sanitation and decreased risks of diarrhea derived from systematic review of RCTs, however only 2 systematic reviews were identified [28,39,58] • Only one study identified showing the association between clean floor and WBD [47] • Intervention studies aimed at improving disposal excreta have found to be protective against diarrhea; however only a few studies in multiple settings were identified and many of them combined other sanitation interventions [19,20,30,34,39,58,104] [27,67] • Distance to water source: increase risk of contamination during transportation from water source to point-of-consumption, and reduce quantity of water from loss during transportation [38,99] • Interruption to use of facilities: households with interruption to water supply had 2.87 higher odds of diarrhea [47] • Underlying scepticism about waterborne disease transmission: villagers believed that WBD outbreak started because of ancestral curse or witchcraft [21] and the lack of health risks in pathogens [32] • Economic hardship: communities had good knowledge but unable to adapt behavioral change due to unaffordability [27] Alternatives for resourcepoor settings

•
Using bottled water when possible [95] • Harvest rainwater and stormwater, or reuse water, to be treated and used along with other WBD interventions [30] • Emphasize the importance of handwashing in educational campaigns as it is less costly compared to other interventions (e.g., filter use) [27,79] • Higher reduction of diarrhea incidence is seen in children receiving intervention with education and handwashing compared to those with education and other interventions [39,50,79,80,99,105] Strength of evidence • Low strength of evidence due to low intervention uptake which confers difficulty in evaluating the impacts of intervention [54] • Significant association between education intervention and reduction in diarrheal incidence as seen in RCTs [39,56,79,102] The majority of the reviewed studies demonstrated positive relationship between primary preventive interventions on diarrhea incidence and disease transmission by ad-dressing WBD associated health risks, however, there is a lack of assessed literature that quantifies the extent of the efficacy of such interventions on disease reduction. In the case of water treatment, many studies conferred a well-established link between less contaminated household drinking water and reduction in diarrhea risk, but not the effectiveness of WBD reduction and associated health outcomes, such as mortality, within the community [29,41,51,55,59,64,70,71,83,85,100,101].

Discussion
This narrative review examined evidence of eight primary preventive interventions against WBDs. The interventions share certain enabling and limiting factors that affect the success of proposed preventative interventions when applied to the health-EDRM framework: resources accessibility and affordability, accommodating community health facilities, correct understanding of WBD associated health risks, sustainable behavioral change, cultural relevance, and cross-sector collaboration with top-down contribution from policy makers. By contrast, socioeconomic barriers, geographical location and cultural incompetence were noted as key limiting factors.

Top-Down, Capacity Building, Cultural Relevance and Post-Intervention Monitoring
Many of the primary preventive interventions examined in this review were complex interventions that relied upon a combination of enabling factors to reduce WBD. For instance, a large proportion of interventions required access to material resources, ranging from simple soap to materials for constructing facilities. However, in very low-resource settings, contributions from authorities and policy-makers are also essential in order to provide these material resources. For instance, in order to ensure sustainable delivery of safe water supply and waste management systems in low income areas, multi-sectoral collaboration and coordination from local and national-level authorities is necessary. Furthermore, in order to successfully implement behavioral interventions such as the appropriate use of prophylactic supplements, government support and capacity within health system is often required. Policy makers should, therefore, re-prioritize the delivery of sustainable water and sanitation services as the importance of safe water access to reduction in WBD incidence has been reinforced in this review.
This review noted that primary interventions for reducing WBDs also often require addressing pervasive misconceptions, attitudes and social norms. For instance, WASHeducation campaigns were successful in teaching participants to associate contaminated water and poor hygiene with diarrhea-related illnesses [26,28,50,77,80,99,105]. These campaigns were successful in increasing positive change in disease prevention behaviors at an individual level, as well as improvements in the hygiene practice of pupils in health education campaigns [35]. Addressing misconceptions (the perception that boiling is sufficient in killing all waterborne microbes [29]), cultural traditions (painting of mud floors with animal dung [47]) and religious beliefs (WBD outbreak as a result of ancestral curse and witchcraft [21]), allows individuals to develop understanding of the rationales behind the preventative interventions. Education and the transfer of knowledge should be delivered in a culturally-sensitive manner, whilst accounting for language needs and health literacy of the target population to guarantee accurate uptake of information [32,102]. The implementation of other primary prevention initiatives should therefore follow the health-EDRM framework with emphasis on capacity building and cultural relevance to prompt long-term positive behavioral changes [11], allowing the evaluation of the real-life impacts and feasibility of interventions. We noted in addition to cultural relevance, intervention adherence requires contextual relevance (improved buckets for water collection were more popular amongst refugee camp inhabitants despite lower effectiveness in water quality protection compared to proper chlorination, as improved features, such as small handle and lid, were more appreciated within the culture [43]). However, this review noted that in some cases, the WBD interventions lacked long-term impacts such as improvements in child health (no difference in prevalence of child diarrhea in post-intervention follow-up [76]), and improvements in hygiene practices (no difference in self-reported handwashing behavior [76], lack of adoption of water treatment into regular household routines despite distribution of filters and soap [21]). These findings may indicate decreasing compliance with interventions with time and the necessity of post-intervention small-scale monitoring to ensure sustainable positive behaviors. Hence, continued behavioral monitoring, such as regular inspection of chlorine levels in house-hold stored water, may be necessary to improve baseline water quality levels and maintain household capacity building.

Long-Term Sustainability and Long-Term Co-Benefits
Many It is important to note that the effect and impacts of preventive interventions are cross-cutting. The uptake of one intervention should not impede the practice of another, and despite the mixed evidence regarding the cost-effectiveness of multi-intervention programs compared to single intervention [19,28,30,34,35,39,[45][46][47]56,58,59,77,87,95,99,104,105], different interventions could be promoted in rural communities to maximize the potential positive health impacts from improved water, sanitation and hygiene behavior. For instance, the construction of community infrastructures, such as filtration system that delivers clean water to storage tanks or directly to homes [54,95], and sewer system that allows safe waste disposal [67], did not only improve access to safe water but also allowed more effective uptake of certain personal and household interventions that rely on adequate baseline water quality in the community. Despite the higher costs in constructing community infrastructure, it has been shown to influence positive behavioral changes within a community (increase in the number of households with hygiene enabling facilities and proper use and maintenance of toilets and sewers [27,67]). This could reduce future expenditures on the prevention of disease outbreak or medical costs for individuals and households. Additionally, lowered medical expenses from reduced incidence of diarrheal illness can allow for greater ability to purchase resources, such as firewood and purifiers, to maintain water quality [26,48,62]. Sustainable and continuous implementation is required for all interventions to ensure maximum efficacy, and alternatives to such behavior should also be explored. Certain interventions, for example, waste management and handwashing, also exert co-benefit in reducing risks from other biological hazards under the health-EDRM framework, such as food-borne, vector-borne and droplet-borne diseases [111][112][113].

Research Gaps Identified in Current Published Literature
This review has identified six major research gaps in the literature relating to health-EDRM primary preventative interventions for WBDs.
First, current studies focus on reducing exposure to hazards, such as contaminated water. A total of 73% of the studies in this review proposed interventions, such as improved water treatment, water storage and waste disposal in household and community settings. There is little evaluation on the efficacy of managing other causal factors of in WBD. Future studies can examine interventions that target hazard preparedness and risk-reduction within exposed populations.
Second, research outcomes are skewed towards reduction in diarrhea incidence, with lack of evidence on the reduction of other WBD-associated symptoms, such as vomiting and stomach cramps [26,35,38]. Diarrhea is a leading cause of mortality and morbidity, especially in children under five years of age, however, it is not the sole indicator of WBD. Nor are WBDs the only cause of diarrhea, as symptoms can be associated with infectious diseases that transmit through other mechanisms, such as HIV and Ebola [114,115]. The observed reduction in incidence of solely diarrhea from an intervention does not necessarily represent the true risk reduction as related to WBDs. The impact of the intervention on WBD prevention is at risk of being overestimated if other diseases are present or underestimated if other symptoms are not considered. Future studies that evaluate the efficacy of primary prevention interventions should consider evaluating non-diarrheal symptoms such as vomiting and stomach cramps along with diarrhea, to strengthen the accuracy and validity of such methods as WBD preventative behavior, particularly in vulnerable or resourcepoor communities.
Third, there is limited research on alternatives of preventive interventions for implementation in resource-poor or material-scarce settings. For example, the beneficial effect of handwashing with soap is consistent across various studies, but there is little evidence to support the use of alternatives, such as ash in communities where soap is not available [2,116]. The efficacy of such alternatives has been demonstrated in averting the transmission of droplet-borne and vector-borne, but not in waterborne diseases [112,113]. As almost 80% of all illnesses and deaths in low and middle-income countries are linked to poor water and sanitation conditions, further evidence-based and scientifically-rigorous studies should be conducted to better inform public health interventions in these contexts where financial and material resources are lacking [117]. The scientific merits of such alternatives should, therefore, be further evaluated and used to build effective strategies in regions that experience physical and economic water scarcity [6].
Fourth, there is inconsistency in the recommendations by research institutions for certain preventive interventions between research institutions. For handwashing interventions, the time required for washing to ensure proper hand hygiene was not specified in most studies [19,20,35,38,42,[45][46][47]60,61,68,72,73,[78][79][80]104,105]. On the other hand, while the WHO defines improved sanitation as better access to sanitation facilities [114], many of the reviewed studies did not specify what measures can be put in place in a household to achieve improved sanitation. There is also lacking evidence in the ways to maintain appropriate use and cleanliness of household and community facilities. This creates challenges in assessing the competitiveness of results.
Fifth, there is little evidence on the efficacy of chemoprophylaxis against WBD. Only one study included prophylactic supplements in their intervention, where a diarrhea pack with water purification sachet was distributed within the community [56]. Comparative evaluation for variation of preventive interventions, such as different types of prophylactic supplements and types of water storage containers are useful in the planning of costeffective interventions and should be implemented in future studies. The use of the more economical regular soap is now favored in most handwashing campaigns as similar reduction in diarrheal incidence has been observed with the use of regular soap and antibacterial soap [68,72]. Due to the search strategy and key words used, vaccination was not identified as an intervention. However, it must be acknowledged immunization has been regarded as one of the most effective primary prevention methods against viral illnesses with observed effects in food-borne and vector-borne diseases [111,112]. Vaccines against typhoid, hepatitis A and cholera are recommended by the WHO to travelers visiting areas of increased WBD risks [118]. Cholera vaccination is also included in routine childhood vaccination programs in many countries worldwide where risk is high, although the high costs of procurement, delivery, and program implementation, coupled with gaps in community education and awareness, are barriers to vaccine delivery in low-income countries where WBD is most prevalent [115].
Sixth, there was limited evidence in comparative evaluation for variations of primary preventive interventions, such as efficacy of the different water storage containers, or different materials to maintain household cleanliness. Strengthening the available evidence in the above-mentioned areas will allow development of strategies for protecting against WBDs in low-resource settings.
This study summarized the most common eight primary prevention interventions identified in WASH-related literature and the strengths and limitations of their implementation to improve Health-EDRM outcomes in low-resource communities. There is value in subsequent studies assessing the risks of WASH at multiple levels as pertaining to these interventions through a number of alternative frameworks, including the WASH cluster strategic operations framework and other ecological models.

Study Strengths and Limitations
There are some limitations to this review. The review excluded non-English-based literature, non-electronically accessible civilian-published literature, grey literature or any publications before 2000. The review also excluded annual reports from specialized organizations, United Nations reports, or reports by national governments. The eight preventative interventions identified in this review do not constitute all of the non-pharmaceutical preventative behavior that is available in the mitigation of WBD. Moreover, this review has not disaggregated findings by pathogen, for example difference in efficacy of interventions between viral, bacterial, and parasitic diseases. This area warrants further research, in order to review predictive success of interventions across different areas with particular disease patterns.
Despite the limitations, this review was able to identify valuable behavioral interventions for the planning and implementation of health policies that prevent water-borne biological hazards. Preparedness in communities facing specific vulnerabilities could be reinforced through multi-faceted and multi-sectoral collaboration, with an emphasis on four key areas (risk understanding, governance, preparedness and resilience) as suggested by the primary prevention model for disaster risk reduction in the Sendai Framework for Disaster Risk Reduction [12].

Conclusions
WBD-associated health risks will remain an ongoing biological hazard to the rapidly globalized world, which highlights the importance of sustainable strategies. In order to meet the SDGs by 2030 [16], multi-sectoral, multi-level capacity building will be needed for sustainable health-EDRM practices, with research for the effectiveness of alternative methods to WBD prevention in low resource settings. The implementation of policies such as early warning systems to inform the associated health risks of seasonal outbreaks and community education that focuses on early symptom identification with subsequent healthseeking behaviors could allow for better prevention and control of unexpected outbreaks. Such policies would also be beneficial in the case of the recent COVID-19 pandemic as low-resource communities are more likely to be affected by the pandemic. Evidence-based research must be translated into feasible and effective actions for disaster risk mitigation and risk reduction.
Supplementary Materials: The following are available online at https://www.mdpi.com/article/10 .3390/ijerph182312268/s1, Table S1: Relevant interventions, study design, relevant key findings, and conclusion of each utilized reference, Table S2: Coding for each type of intervention in Table S1.

Conflicts of Interest:
The authors declare no conflict of interest.

Appendix A
Pathogens transmitted through drinking water are diverse in causative agent, characteristics, and health significance. Table A1 shows pathogens that are globally significant for water safety and supply management [119].