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date: 21 March 2023

Water Safety Plansfree

Water Safety Plansfree

  • Karen SettyKaren SettyICF International Inc Durham
  •  and Giuliana FerreroGiuliana FerreroIHE Delft Institute for Water Education


Water safety plans (WSPs) represent a holistic risk assessment and management approach covering all steps in the water supply process from the catchment to the consumer. Since 2004, the World Health Organization (WHO) has formally recommended WSPs as a public health intervention to consistently ensure the safety of drinking water. These risk management programs apply to all water supplies in all countries, including small community supplies and large urban systems in both developed and developing settings. As of 2017, more than 90 countries had adopted various permutations of WSPs at different scales, ranging from limited-scale voluntary pilot programs to nationwide implementation mandated by legislative requirements. Tools to support WSP implementation include primary and supplemental manuals in multiple languages, training resources, assessment tools, and some country-specific guidelines and case studies.

Systems employing the WSP approach seek to incrementally improve water quality and security by reducing risks and increasing resilience over time. To maintain WSP effectiveness, water supply managers periodically update WSPs to integrate knowledge about prior, existing, and potential future risks. Effectively implemented WSPs may translate to positive health and other impacts. Impact evaluation has centered on a logic model developed by the Centers for Disease Control and Prevention (CDC) as well as WHO-refined indicators that compare water system performance to pre-WSP baseline conditions. Potential benefits of WSPs include improved cost efficiency, water quality, water conservation, regulatory compliance, operational performance, and disease reduction. Available research shows outcomes vary depending on site-specific context, and challenges remain in using WSPs to achieve lasting improvements in water safety. Future directions for WSP development include strengthening and sustaining capacity-building to achieve consistent application and quality, refining evaluation indicators to better reveal linked outcomes (including economic impacts), and incorporating social equity and climate change readiness.


  • Disaster Preparation & Response
  • Environmental Health
  • Epidemiology
  • Global Health
  • Public Health Policy and Governance

What Are Water Safety Plans?

The World Health Organization (WHO) recommends a holistic risk assessment and management approach, called a water safety plan (WSP), for all water suppliers (WHO, 2004). WSPs systematically identify hazards that may be introduced along the water supply chain, from the land area collecting rainfall (i.e., watershed or catchment) to the water source (e.g., a lake, river, reservoir, or aquifer), treatment facility, and point of use or consumption. The approach to WSP development and implementation mirrors risk assessment and management approaches used in many other industries. Key components include understanding the risks, establishing control measures for the greatest risks, and applying monitoring, review, and management measures to ensure the risks remain under control. The WSP manual (Bartram et al., 2009) and other training materials (see WHO, 2012a) provide greater detail on the WSP process broken down into “modules,” which correspond to a simplified approach for small community water supplies (Table 1).

Table 1. Overview of Water Safety Plan (WSP) Steps

WSP Components (Stages)

WSP Steps (Modules)

Module Overview

Tasks (for small community water supplies)


Assemble the WSP team

What we do: Form an experienced, multidisciplinary team to undertake the WSP

Why we do it: To establish a body responsible for development and ongoing implementation of the WSP

How we do it: Identify key team members (internal and external to the water supplier), assign roles and responsibilities and secure commitment

Engage the community and assemble a WSP team

System assessment

Describe the water supply system

What we do: Develop a detailed, up-to-date description of the complete water supply system

Why we do it: To contribute to system understanding and to facilitate subsequent identification of system vulnerabilities

How we do it:


Identify intended users and uses of the water


Provide detailed system information (including diagrams)

Describe the community water supply

Identify hazards and hazardous events*

What we do: List the issues that may threaten the safety and security of the water supply

Why we do it: To understand what could go wrong with the water system, and where and how to allow for risk assessment and risk management

How we do it: For each step in the water supply chain, identify hazards and hazardous events that could contaminate or compromise the water supply

Identify and assess hazards, hazardous events, risks, and existing control measures

Determine and validate control measures, then assess and prioritize the risks

What we do: Evaluate control measures already in place to protect the water supply, validate the controls, and assess risks in light of controls

Why we do it: To understand how well the hazardous events are already controlled to prioritize improvement needs

How we do it:


Identify existing control measures


Validate control measures


Assess residual risk

Develop, implement, and maintain an improvement/upgrade plan

What we do: Develop a detailed improvement plan to address all risks requiring additional control

Why we do it: To ensure stepwise system improvement

How we do it: For risks not adequately controlled, decide on appropriate action and put in place an improvement plan to ensure action is taken

Develop and implement an incremental improvement plan


Define monitoring of the control measures (operational monitoring)

What we do: Define an operational monitoring plan for control measures

Why we do it: To ensure that the control measures continue to work as intended and to allow for timely action to be taken to prevent problems from occurring

How we do it: Develop a practical monitoring plan for control measures, including establishing critical limits and defining corrective actions to be taken when needed

Monitor control measures and verify the effectiveness of the WSP

Verify the effectiveness of the WSP

What we do: Confirm that drinking water quality standards are being met, consumers are satisfied and the WSP is complete, up-to-date, and effective

Why we do it: To verify that the WSP as a whole is working effectively

How we do it: Carrying out the three elements of the “verification triangle” (monitor water quality to confirm compliance, monitor customer satisfaction, and audit the WSP)

Management and communication

Prepare management procedures

What we do: Document management procedures to be followed during normal conditions and in incident or emergency situations

Why we do it: To ensure that all staff clearly understand what to do and when

How we do it:


Develop standard operating procedures (SOPs)


Prepare emergency response plans

Document, review and improve all aspects of WSP implementation

Develop supporting programs

What we do: Develop supporting programs

Why we do it: To contribute to drinking-water safety

How we do it: Develop or strengthen programs that indirectly support water safety, such as operator training programs and consumer education programs

Feedback and improvement

Plan and carry out periodic review of the WSP

What we do: Review and revise the WSP regularly

Why we do it: To ensure that the WSP is up-to-date and effective

How we do it: Plan and conduct WSP reviews regularly

Revise the WSP following an incident

What we do: Review and revise the WSP after an incident

Why we do it: To ensure that the WSP reflects lessons learned from incidents and near misses

How we do it: Plan and conduct WSP reviews as needed

* Alternatively, inherent (or raw) risk can be assessed at this stage for comparison with the residual risk assessed in Module 4, Determine and validate control measures, then assess and prioritize the risks, as presented in the WSP manual (Bartram et al., 2009) and WSP training package (WHO, 2012a).

Source: Adapted from Bartram et al. (2009) and WHO (2012a, 2012b, 2019).

While completing the modules or tasks, practitioners adhere to several main concepts (Bartram et al., 2009). First, the WSP should be considered a holistic approach to consolidating different risk assessment and management activities. Second, although taking small steps may be helpful in getting started, the WSP requires completion of all components to function as intended (Table 1; WHO, 2017b). Third, WSPs should be dynamic (i.e., adaptive to shifting conditions) and practical (i.e., straightforward for users to implement, for instance via integration into standard operating procedures). Fourth, for large systems or those with adequate resources, implementers should retain accurate records to transparently document and justify decisions and to demonstrate consistently safe operation.

WSPs represent a team-based, multiorganizational intervention (Baum et al., 2015); for example, participants may include household water users as well as environmental, conservation, agriculture, engineering, and health organizations. Implementers should work to secure buy-in from leaders, employees, and stakeholders prior to initiation—for example, to ensure readiness among community members and politicians to support the water supplier in undertaking a WSP (Bartram et al., 2009; Kot et al., 2015; Summerill et al., 2010). To ensure success, all levels of the organization must advocate for the WSP method (Summerill et al., 2010). Managers should be cognizant that organizational culture will influence WSP effectiveness and recognize their critical role in developing a supportive climate. The WSP tenet of “no-blame” review reinforces the idea that staff involved are not individually responsible for failures; rather, they represent an opportunity for the whole team to learn about, and improve, conditions for addressing risks (Bartram et al., 2009). Reinforcing the public health responsibilities of the organization among all staff, contractors, and community partners, who may be water customers living in the service area themselves, can help generate buy-in (Kayser et al., 2019; Summerill et al., 2010).

Because WSPs involve many moving parts (i.e., multiple actors, actions, and areas of change), the process of adapting the general guidance (e.g., Table 1) brings added complexity. Some core components of WSPs are maintained in all implementation cases, while other variables are modified to meet the specific location’s needs, setting, and context (Setty, 2019). For instance, the team members, risk-rating methodology, high-priority risks, and management strategies will likely vary across different water suppliers. Some large urban WSPs may rely heavily on technology for operational monitoring (e.g., sophisticated laboratory testing, real-time water quality sensing, and automated alarms), whereas other WSPs may be adapted to low-resource, small, or rural community systems (e.g., relying on periodic visual inspections; String & Lantagne, 2016; WHO, 2012b). The process of adapting to both site-specific information and changing risk scenarios over time remains a critical part of achieving long-term risk reduction (Bartram et al., 2009).

History of WSPs

The WSP concept originated with performance of routine “sanitary inspections” of water supply systems in the early 20th century. These inspections follow a short, standardized observational checklist to assess risks to public health. They were first promoted by WHO in the 1976 monograph “Surveillance of Drinking-Water Quality” and have since been mentioned in each edition of the WHO guidelines for drinking-water quality (Kelly et al., 2020). Another key predecessor of WSPs was the hazard analysis and critical control points (HACCP) process. In the 1960s, the U.S. Army Laboratories, U.S. National Aeronautics and Space Administration (NASA), and a packaged food company (Pillsbury) teamed up to develop an approach aimed at preventing hazards, rather than testing the safety of a product retrospectively. This food-safety management process was well established by the 1990s (Havelaar, 1994), leading to formation of the International HACCP Alliance. Iceland first adopted national legislation applying the HACCP concept to public drinking-water supplies in 1995 (Gunnarsdottir & Gissurarson, 2008). HACCP and similar International Organization for Standardization (ISO) standards (i.e., 9001, 14001, 22000, 31000) remain in widespread use for food safety, manufacturing, engineering, and other business applications.

Other ideas contributing to preventive management have included failure mode analysis, multiple barriers, continuous quality improvement, total quality management, and quantitative microbial risk assessment (QMRA). The QMRA concept also originated in the food industry and was first proposed for water safety management in the 1990s (Regli et al., 1991). QMRA has been used in various applications, including drinking water, recreational water, and water reuse, and it has been embedded in the WHO guidelines (WHO, 2016a).

In 2004, after a decade-long global consultation process involving more than 500 individuals from approximately 100 countries, the third edition of the WHO guidelines for drinking-water quality carried a global recommendation for WSPs (WHO, 2004). The International Water Association (IWA), a global professional association, echoed this recommendation in the Bonn Charter for Safe Drinking Water (IWA, 2004). The first edition of the WSP manual was jointly released by WHO and IWA in 2009 (Bartram et al., 2009).

Evolution of the Concept Over Time

As WSP application expands around the world and more case studies and research become available, the spatial scale, scope, and expected outcomes continue to evolve.

Regarding scale, WSPs designed at a watershed level have been adapted to serve the needs of urban areas, individual buildings (e.g., hospitals), ships, sanitation systems, and direct potable reuse systems (see Almeida et al., 2014; Goodwin et al., 2015; Mouchtouri et al., 2012; WHO, 2011). The practice of safe wastewater management via sanitation safety plans (SSPs) was introduced by the 2006 WHO Guidelines for the safe use of wastewater, excreta and greywater (WHO, 2006). The SSP concept, which mirrors WSPs, applies the risk assessment and management approach from the point of wastewater generation (e.g., the toilet, sink, or shower) to the final use or disposal (WHO, 2016b). SSPs operate in a less-defined regulatory environment than WSPs, but they also have multiple objectives and stakeholders (e.g., wastewater utility managers, sanitation enterprises, farmers, and community-based organizations; Winkler et al., 2017). They address risks to multiple exposure groups, such as sanitation workers, farm workers, local communities, and consumers who eat or use agricultural products produced using recycled wastewater, biosolids, or fecal sludge.

Water cycle safety plans (WCSPs) have been developed under the framework of the PREPARED research project funded by the European Commission to provide a risk management approach for the entire water cycle, including water supply, wastewater treatment, water reuse, and management of water bodies (Almeida et al., 2014). Subsequently, another European Union (EU) project, DEMOWARE, aimed to develop and promote adoption of a risk management framework for water reuse by integrating elements of WSPs, SSPs, and WCSPs (Hochstrat et al., 2017). As water reuse applications expand in the future and blur the lines between “new” and “recycled” water, different types of water safety and environmental stewardship programs are increasingly likely to be combined.

Regarding scope, numerous parties have proposed add-ons, revisions, or adaptations of the guidance on WSP implementation in the literature and specific country or regional policies (WHO & IWA, 2020). For example, the Techneau project funded by the European Commission developed a set of tools for risk assessment and risk management, including a hazard database, a risk-reduction option database, a decision-support tool integrating asset management and cost optimization, and an integrated and quantitative risk model for comparing risk reduction alternatives (Rosén et al., 2009). Some countries, such as the Netherlands, use a more complex risk assessment and risk management strategy, where one of the key elements is QMRA implementation (van den Berg et al., 2019). In comparison to WSPs, QMRA provides a numerical output of estimated health outcomes from microbial hazards that may support risk management in finer detail than qualitative (e.g., sanitary inspections) or semi-quantitative (e.g., WSP) approaches (WHO, 2016a). Sanitary inspection guidance from the WHO is similarly under review, with the goal of better aligning this low-cost approach, commonly practiced in developing settings, with WSPs (Pond et al., 2020).

In Canada, Bereskie et al. (2017) proposed implementation of WSPs along a timeline akin to plan-do-check-act (PDCA) quality improvement cycles, which are used prominently in the clinical healthcare industry. Some water supply organizations (e.g., in Australia) integrate WSPs with organization-wide business and financial risk planning, for example by having separate business units (a) to propose appropriate technical risk management solutions and (b) to select the most effective solution based on cost, client relations, and environmental impacts (Setty et al., 2019a). In 2019, the Joint Research Center of the European Commission published a document for water utility operators on water security planning; it aimed to provide clear guidance for unexpected water security emergencies and recommended integrating security planning with the WSP approach where possible (Teixeira et al., 2019).

The evolving scope of WSPs has increasingly refocused attention on the hazards posed by global climate change, which is projected to cause more frequent and severe extreme weather events (WHO, 2017a). The potential for WSPs to address social equity has also been highlighted, especially since the 2015 global emphasis on Sustainable Development Goal (SDG) 6 (“Ensure availability and sustainable management of water and sanitation for all”), and is reflected in a targeted guidance manual for equitable WSPs (WHO, 2019). As of 2020, WHO has undertaken a comprehensive review and revision effort to appropriately integrate these and other concepts into WSP practice, with the goal of issuing an updated second edition of the WSP manual. Evaluation approaches are similarly evolving as experience with WSP implementation and outcome measurement expands (discussed further under “Evaluating Impacts”).

Global Uptake and Relationship to Policy

Drinking-water risk management interventions have spread rapidly since the formal WHO recommendation in 2004 (WHO, 2004). As of 2017, WSPs had been implemented in more than 90 countries (see WHO, 2017b, Figure 2). Implementation is expected to continue to increase as many strive to address the SDG indicator 6.1.1 of “safely managed drinking water.”

The combination of available guidelines, regulations, tools, resources (technical, human, and financial), support, and evidence associated with WSP implementation constitutes what is termed the “enabling environment,” or the conditions that make it possible to effectively implement the intervention (Baum & Bartram, 2018). On an international scale, highly visible and respected guidelines and standards (e.g., from WHO, IWA, and ISO) have promoted WSP adoption and implementation. At the national and state level, public health agencies that increasingly recognize the limitations of end-product testing have contributed to WSP policy development (Baum & Bartram, 2018). As of 2020, WSPs were nationally legislated (promoted or required) in approximately 61 countries, including Australia, New Zealand, Serbia, Switzerland, Uganda, and the United Kingdom (Baum & Bartram, 2018; WHO, 2017b, Figure 6; A. Rinehold, personal communication, August 19, 2020). Legal requirements drive WSP engagement by water suppliers and reinforce the relevance of auditing WSPs. Legislation can also mobilize resources for WSP implementation, particularly for small systems (Schmoll et al., 2011).

Models of regulatory implementation vary among countries (Baum & Bartram, 2018; WHO, 2017b). Some countries (e.g., New Zealand, Peru) have adopted multinational or national legislation, while others (e.g., Canada, Australia) have large separate states that independently adopt requirements for WSPs. Policy instruments for WSP adoption vary in terms of flexibility, the promulgating agency, format (e.g., acts, regulations, standards, frameworks, policies, and strategies), and the formal review and approval process. Japan, for example, issued voluntary guidelines in 2008 to promote WSPs rather than requiring them via legislation. In the EU, Directive 2015/1787 gave member states and other countries the option to deviate from required drinking-water monitoring parameters and minimum monitoring frequencies where a different risk assessment program comes into use (WHO, 2017b). A pending revision the EU Drinking Water Directive (COM/2017/0753) would require all member states to promulgate WSPs. Legislative bodies, environmental protection agencies, and public health agencies may participate in policy coordination and oversight.

However, policy is not the only element of the enabling environment. Even where WSP policies exist, enforcement mechanisms may be lacking (Kanyesigye et al., 2019). Other enabling factors include sociocultural norms, inclusion of WSPs in national strategy, implementation support activities, financial instruments, and external quality assurance (Baum & Bartram, 2018; Omar et al., 2017; Schmiege et al., 2020). The international road map for WSP implementation (WHO & IWA, 2010) provides steps to guide countrywide scale-up:


understand and appreciate the benefits of a WSP approach,


establish a preliminary WSP vision,


attain practical WSP experience,


establish a national strategy to scale up WSP implementation,


establish mechanisms for ongoing support of WSPs,


establish policy and regulatory instruments to support WSP implementation,


implement WSPs and verify their effectiveness, and


review overall WSP experiences and share lessons learned.

In Germany’s experience, for example, stakeholder engagement, guidance documents, and workshop materials have been critical to country-level information dissemination; nonetheless, there is limited information on developing a national strategy, securing financial instruments, supporting WSP implementation, and sharing lessons learned (Schmiege et al., 2020).

At the local level, implementation of pilot WSPs provides context-specific evidence of the feasibility and benefits of WSP implementation in various countries, which in turn influences national guidelines and policies (Baum & Bartram, 2018). While some countries, such as Iceland, represented “early adopters” according to diffusion of innovation theory, other countries where WSPs have not been adopted voluntarily or have not been integrated into regional policies may represent “laggards,” where additional barriers exist, requiring additional or novel implementation strategies (Setty, 2019). For example, the United States may be slow to implement preventive risk management approaches due to the substantial burden of existing regulatory programs, the difficulty of de-implementing entrenched practices, and the resulting low willingness and perceived ability of individual utilities to invest in new approaches (Amjad et al., 2016; Setty et al., 2019a). In a global survey, many respondents raised concerns related to financing WSPs, although implementation progress to date has demonstrated the feasibility of adapting WSPs to resource-limited settings (WHO, 2017b). Financial barriers, whether actual or perceived, must be addressed by providing choices to community decision makers (Herschan et al., 2020). Rather than securing new funding, the most important factors driving successful WSP implementation in small systems in low-income countries were found to be development of technical capacity, community engagement, monitoring and verification, hygiene promotion, and simplicity.


WHO and IWA have produced prolific WSP guidance and training materials as well as a “road map” to resources (WHO, 2017c). Such tools cover guidance on development and implementation, risk management at specific points in the water supply system (e.g., groundwater, surface water, distribution systems, buildings), policy, audit and assessment, training materials, and linkage to other initiatives (e.g., climate change, equity). WHO and IWA (2020) established an online platform, called the Water Safety Portal, designed to promote interaction among governments, practitioners, and implementers and to serve as a consolidated resource library specific to WSPs.

Training is fundamental to building WSP implementation capacity and preparing practitioners to perform WSP-related tasks. Different training formats include face-to-face, online, blended, peer-to-peer, or communities of practice (Ferrero et al., 2019). Groups providing WSP training and auditing support range from water supply associations, operators, and national authorities to universities and private consultants. Training plans may apply a combination of lectures, case studies, practical exercises, technical training elements, role-play activities and other games, field visits, and supervised “on-the-job” training (Ferrero et al., 2019). Training is often required at startup and at regular ongoing intervals to maintain awareness of WSP concepts and procedures. Different formats, levels, and goals of WSP training should target different audience needs, including operating staff as well as senior decision makers, key external stakeholders, and contractors who provide related services (Ferrero et al., 2019; Kayser et al., 2019).

Adapting the WSP approach for the local context and developing customized tools to support field-level implementation are promoted as good practices (WHO EURO, 2016). The importance of nationally adapted background documents, manuals, templates, and other tools in local languages has been stressed (Schmoll et al., 2011; Sutherland & Payden, 2017). Adaptation measures include training in local languages to engender ownership and to sustain WSP implementation (Ferrero et al., 2019). Small systems particularly benefit from this approach (WHO, 2012b).


Evaluation of WSPs has taken the form of both qualitative and quantitative methods to describe implementation processes, completion, challenges, enabling factors, impacts, and outcomes at many locations around the world (WHO & IWA, 2020). Starting in 2011, WSP evaluation methods began to be standardized using a framework and indicators developed by the Centers for Disease Control and Prevention (CDC, 2011; Gelting et al., 2012; Lockhart et al., 2014). The CDC evaluation framework follows a logic model spanning inputs, activities, outputs, outcomes, and impacts. Some implementation-related changes (e.g., funding inputs and meeting activities) may be observed within months, while longer-term impacts (e.g., changes to water supplies and health) may take one or more years to observe (CDC, 2011).

Adaptation of the WSP’s implementation process to fit a water system’s site-specific needs and management priorities may correspond to variability in the WSP’s targeted outcomes, although this area is understudied (Kumpel et al., 2018; Setty et al., 2017). Evaluations may intentionally separate measures of implementation outcomes (i.e., fidelity to the intervention) from measurement of the intervention’s outcomes (Setty, 2019). In Iceland and the Asia-Pacific region, audit scores assessing WSP implementation completeness were not significantly related to measured intervention outcomes and impacts (Gunnarsdóttir et al., 2012; Kumpel et al., 2018). Coupled “hybrid” evaluation designs assessing both the implementation process and impacts of the intervention at the same time may provide a resource-efficient option for cases of prospective WSP implementation (Curran et al., 2012).

Evaluating Implementation

Periodic auditing (or independent assessment) is a vital tool for sustaining and improving the WSP (WHO & IWA, 2015). Third-party review helps to maintain elements of standardization across locations, to demonstrate compliance with regulatory or voluntary standards, and to demonstrate the WSP is complete and accurately recorded as implemented in practice. The WSP manual strongly recommends audits be conducted in a supportive, rather than punitive, manner to reveal areas of potential system-wide improvement (Bartram et al., 2009). A guide to auditing WSPs was developed in 2015 (WHO & IWA, 2015), followed by the WSP audit training package in 2019. Audits can be “internal” when carried out by someone employed or contracted by the water supplier (but independent of the WSP team), or “external” when implemented by a government body or other entity outside of the water supplier. Audits are “formal” when they are used to confirm compliance with regulatory requirements or for organizational quality assurance purposes; “informal” audits are used to provide advice and for learning purposes.

Despite their promotion, global auditing uptake and practices remain inconsistent (Ferrero et al., 2019). The lack of auditor training and certification schemes represents a bottleneck contributing to incomplete or inaccurate WSP implementation. Only a few documented examples of such certification systems are available (e.g., State of Victoria, Australia; WHO & IWA, 2015). Organization of regional, national, or multicountry guidance and certification systems for auditors could improve consistent application of WSP auditing (Ferrero et al., 2019; Schmiege et al., 2020) and produce additional helpful data about how implementation processes and adaptation affect WSP outcomes and impacts (see “Evaluating Impacts”).

Audits may clarify how basic adherence to WSP guidance on a larger scale balances with the need for site-specific adaptations, eliciting potential areas of adjustment for future quality improvement efforts. Quality improvement and implementation tools from related disciplines, such as clinical healthcare, may prove valuable, especially in challenging cases of WSP implementation (Setty, 2019). These tools, such as implementation frameworks, implementation strategies matched to site-specific barriers, timed quality improvement cycling, process theories linking specific inputs to outcomes, and contextual factor checklists, were designed to help move effective evidence-based public health interventions from pilot applications to full-scale application. Some implementation tools may require adaptation (e.g., of terms, definitions, and constructs) to shift from a clinical healthcare context to the water supply industry (Setty et al., 2019b). Although few examples have been applied to WSP implementation to date (e.g., Bereskie et al., 2017; Omar et al., 2017; Setty et al., 2019a), they offer an option for use in WSP research or for addressing recurring or stubborn water safety issues.

Evaluating Impacts

Since 2011, specific WSP impact evaluation indicators have been refined with added research, including a targeted investigation of 99 water supply systems across 12 countries in the Asia-Pacific region (Kumpel et al., 2018). Building on the body of available evidence, practical impact evaluation assessment guidance incorporating climate resilience is under development by WHO to help guide users toward consistent, rigorous methods. Recommended WSP evaluation categories group policy, operational, financial, institutional , climate, water supply, and health indicators (Table 2). Water system managers may opt to supplement, reduce, or adapt the precise evaluation indicators based on their available data, study design, and local contextual factors. Evaluations should ideally be conducted at baseline (prior to WSP implementation) and at regular intervals after WSP initiation. Where baseline data are not collected prior to WSP implementation, baseline conditions can, in some cases, be established retrospectively (Kumpel et al., 2018).

Table 2. Example Indicators for Water Safety Plan (WSP) Evaluation

Framework Category

Indicator Category

Indicator Group




Formal regulatory changes

Risk management approaches included in formal water-sector policies or regulations


Changes in system infrastructure

Infrastructure improved or added as a direct result of the WSP

Changes in operations and management procedures

Level and strength of operations and management practices


Changes in cost recovery

Total revenue as a percentage of total operating costs

Changes in financial support and investment

Financial support leveraged as a direct result of the WSP


Changes in stakeholder communication and collaboration

Number of documented internal and external water safety meetings

Number of consumer water safety training or awareness-raising events


Changes in consideration of climate resilience

Extent to which climate resilience was explicitly considered by the water supplier


Water supply

Water service changes

Service hours as a percentage of continuous supply

Percent water loss from piped systems

Hours of supply interruptions due to extreme weather

Water quality changes

Water quality monitoring practiced

Rate of compliance

Water quantity changes

Source water diversification

Source water production capacity

Available water per capita

Consumer satisfaction changes

Consumer satisfaction surveys conducted

Level of consumer satisfaction

Consumer complaints recorded

Percentage of consumers complaining


Changes in incidence of water-related illness

Cases of water-related illness

Diarrhea incidence

Evaluating Public Health

When implementing WSPs, Summerill et al. (2010) suggested public health should be considered the primary motivator among other legitimate drivers, such as political or stakeholder priorities or financial efficiency. However, the Asia-Pacific impact assessment highlighted that health indicators were particularly challenging to quantify (Kumpel et al., 2018). Since protecting consumers’ health is the core objective of WSPs, the authors called for robust and standardized monitoring methods.

Health impact evaluation for WSPs is challenged by both the quality of health data (Setty et al., 2017) and limited epidemiological study design options (Kumpel et al., 2018). In theory, certain conditions must apply before pathogens can cause a detectable health outcome, such as acute gastroenteritis (diarrhea and/or vomiting). For instance, pathogens must:

be present and viable in ambient source waters,

remain viable through treatment processes and distribution systems or be introduced into onsite storage or handling,

be consumed in adequate amounts to cause infection in a susceptible host,

lead to symptom development, and

cause severe enough symptoms to warrant reporting and/or seeking treatment.

Because many instances of drinking water contamination do not meet all of these (or other) conditions, and because acute gastroenteritis is typically self-treated and self-limiting, public health surveillance often detects only a small fraction of cases. Other factors influencing data capture include when healthcare facilities are open, healthcare affordability, temporality in wage or pension distribution, travel in or out of service areas, and ambient temperatures that exacerbate dehydration symptoms (Bounoure et al., 2020; Setty et al., 2018a).

Variability in public health surveillance approaches across locations and over time may hamper detection of significant changes (Kumpel et al., 2018; Setty et al., 2017). Depending on the local health systems and context, fewer than an estimated 2% to 3% of all acute gastroenteritis cases may be identified through hospital-based surveillance systems (Setty et al., 2017). A novel approach used in France since 2010 detects an estimated one third of all cases using algorithm processing of medication reimbursements from the state-run healthcare system (Bounoure et al., 2020). In addition to its underreporting, diarrhea may be chronic (e.g., associated with other health issues or chronic pathogen exposure in environments lacking adequate human and animal sanitation infrastructure), making it difficult to define individual cases or to assign clear causation. Where public health surveillance data are inadequate, household surveys to quantify the incidence of diarrhea are preferred over questionnaires completed by the water supplier or review of existing household data (Kumpel et al., 2018). Still, self-reported data may be affected by recall bias. If possible, surveys should be implemented using appropriate sampling strategies (e.g., stratified random sampling with adequate power to detect statistical trends).

Epidemiological study design for WSP evaluation requires careful attention due to several additional challenges. First, cases of acute gastroenteritis are more commonly attributed to foodborne or person-to-person transmission than to drinking water. The disease burden attributable to drinking-water exposure may be a small percentage of total cases, especially in developed settings (Setty et al., 2017). Second, seasonal trends in diarrheal diseases are also common, with person-to-person viral transmission more common in the winter months or rainy seasons, depending on climate (Ahmed et al., 2013). Microbial infectivity can also fluctuate over time as different strains of pathogens become more or less prominent. Third, water suppliers and healthcare facilities may cover different service areas, with some populations served by multiple, mixed, or overlapping drinking-water systems or sources (Setty et al., 2017).

Robust study designs must take these underlying influences and background levels into account, preferably by comparing a WSP location to a baseline period before the WSP was implemented, or a comparable area nearby that did not undergo WSP implementation. Since WSPs are recommended for all locations to achieve improved drinking-water safety, it may be unethical to randomize assignment of the intervention for long periods, although using stepped-wedge designs or temporarily delaying WSP implementation may provide acceptable research alternatives. To establish causality, controlled prospective study designs (i.e., where the outcome has not occurred when the study starts and subjects are followed over a period) are typically the gold standard, but also require the most resources and expertise. Before–after or interrupted time series (“quasi-experimental”) designs may be more appropriate and practical to provide evidence of association of observed changes with WSP implementation over time (Kumpel et al., 2018; Setty et al., 2018a). Randomized controls (i.e., locations where a WSP is not implemented to understand background changes unrelated to the intervention) may be difficult to identify if the pool of candidate water suppliers is limited, but matched controls can be selected based on characteristics such as water system size, geographic setting, and/or revenue (Kumpel et al., 2018; Setty et al., 2017).

These challenges highlight the need for robust public health systems and regular communication and cooperation between health and environmental (i.e., water management) authorities to support ongoing WSP improvement.

Benefits and Challenges

Public Health Impact

Promising studies on public health outcomes of WSPs have been conducted in Iceland, France, and Spain, demonstrating potential for population-level declines in diarrheal disease rates (Gunnarsdóttir et al., 2012; Setty et al., 2017). Given Iceland’s earlier start using WSPs, they produced the earliest evidence of public health impacts (Gunnarsdóttir et al., 2012). Research found that populations served by an unchlorinated groundwater supply with a WSP in place had 14% fewer clinical cases of diarrhea on average compared to pre-WSP conditions. Follow-up research examining chlorinated surface and groundwater suppliers in France and Spain demonstrated a reduction in acute gastroenteritis incidence following WSP implementation at one of three locations examined, corresponding to about a 4% decrease in acute gastroenteritis incidence in the overall population, or 6% among adults (Setty et al., 2017). Although these percentages form a small proportion of the overall diarrheal disease burden, they likely represent a sizable portion of the burden attributable to drinking-water exposures. Using a time-series design at the same locations in France and Spain, Setty et al. (2018a) showed specific risks associated with surface runoff into water supplies and increased source water turbidity were likely mitigated by WSP-related treatment interventions, adding to the evidence that the health changes were associated with WSP implementation. In the Asia-Pacific region, data on the incidence of diarrheal disease were rarely adequate to assess changes (Kumpel et al., 2018). Taken together, the health impact results suggest the WSP approach to site-specific risk management is potentially effective at reducing baseline gastrointestinal illness risk. Evidence regarding the capacity of WSPs to prevent unexpected, low-frequency but high-impact events (e.g., outbreaks) is more challenging to ascertain quantitatively.

Related Benefits

Although positive, neutral, and negative outcomes (e.g., Setty et al., 2017) have been documented at various WSP implementation locations in the primary evaluation categories (Table 2), most literature shows some aspects of improvement within the first few years of programming (WHO & IWA, 2020).

The most common category of improvement was operations and management (at 95% of evaluated sites), followed by infrastructure improvements (at 86% of evaluated sites) in the Asia-Pacific impact assessment (Kumpel et al., 2018). Case studies from other world regions have similarly shown operation and maintenance shifts to be a key driver of WSP-related benefits (Setty et al., 2018b; String & Lantagne, 2016; String et al., 2020; WHO & IWA, 2018). While risk reduction is hard to measure on brief time scales and without random controls, qualitative evidence and managers’ experience following adoption of WSPs has highlighted better control of hazards that were previously overlooked (Kayser et al., 2019).

Water quality and communication among water suppliers and stakeholders similarly show improvement at a majority of WSP locations (Kayser et al., 2019; Kumpel et al., 2018; Setty et al., 2017). Water quality improvements have also been reported, albeit inconsistently, in community-managed water supplies in developing nations (Mahmud et al., 2007; String et al., 2020). Water quality changes may correspond to more consistent achievement of regulatory or voluntary compliance thresholds developed for public health protection (Gunnarsdóttir et al., 2012; Setty et al., 2017); however, these indicators are limited because most provide only a surrogate for pathogen exposure and disease risk.

A 2016 systematic review found limited evidence to support financial improvements in Uganda and Palau, related to reduced monitoring costs and water conservation (String & Lantagne, 2016). Another five-country study enumerated typical startup and maintenance investments in WSPs (Kayser et al., 2019) but did not monetize benefits. Data on financial benefits would be valuable because much of the socioeconomic impact of WSPs could stem from fewer sick days, reduced healthcare expenses, and greater worker productivity, which benefit disadvantaged groups and other industries beyond the water supplier.

Ongoing Challenges

Despite the potential benefits of WSPs, many actors remain undecided about whether to promote or mandate WSP policies. Review of WSP uptake in high-income countries shows policies, support from public health agencies, and context-specific evidence of the feasibility and benefits have played an important role in enabling widespread adoption and implementation (Baum & Bartram, 2018). Conversely, a paucity of context-specific evidence, inadequate training, impediments to knowledge translation, insufficient financial or human resources, or skepticism about return on investment might forestall decision and implementation processes (Amjad et al., 2016; Ferrero et al., 2019; Kayser et al., 2019). Country-specific cultural influences and the political economy, including local community readiness, are also expected to influence WSP feasibility (Kot et al., 2015; Omar et al., 2017). Decision makers may wait for others to furnish local evidence, requirements, or incentives before adopting new programs. Translational research (Setty et al., 2019b) to pilot, evaluate, and effectively replicate novel WSP programming can play an important role in actively enhancing the enabling environment for WSP scale up.

Securing collaboration among the broad range of stakeholders involved in WSPs may be challenging, especially when implementing improvement plans that fall outside the direct authority or management purview of the water utility (Ferrero et al., 2018). Another common challenge relates to initial improvement upon WSP adoption that is not maintained over time (i.e., “backsliding”). WSP implementation may be incomplete, fail to translate to expected outcomes, or inadvertently result in harmful outcomes (Kanyesigye et al., 2019; Setty et al., 2017; String et al., 2020). For instance, acute gastroenteritis rates remained steady or worsened following WSP implementation at some locations (Setty et al., 2017, 2018a, 2018b), where multiple management changes took place concurrently (e.g., improving maintenance of chlorination while also retaining turbid water to augment quantity). Altering disinfection methods to reduce pathogens, if not done cautiously, could at the same time lead to increases in exposure to carcinogenic disinfection byproducts (Setty et al., 2017). Consistent vigilance, buy-in, trialing and adjustment, accessibility of procedures, and ease of use are critical to sustain gains achieved through these programs.

Finally, impact assessment research has been carried out unevenly throughout the world, highlighting research imbalances between the Global North and the Global South. In particular, limited evidence is available from the African continent, with only two studies carried out in rural settings in South Africa (Mudau et al., 2017) and the Democratic Republic of Congo (String et al., 2020) and one countrywide study in urban settings in Uganda (Kanyesigye et al., 2019).

Future Needs and Directions

Continuous capacity-building is fundamental to sustaining meaningful WSP implementation. Researchers and practitioners should focus on developing methods to monitor WSP capacity sufficiency and capacity development. The importance of auditing as a summative assessment method cannot be overstated. Additionally, legally requiring qualification and training of all water operators may help mobilize resources for WSP training, particularly for small systems (Ferrero et al., 2019). Evidence from an operational research study in India, Democratic Republic of the Congo, Fiji, and Vanuatu (String et al., 2020) delineated these recommendations on the path forward for rural community-managed WSPs:

simplify tools,

motivate community-level WSP uptake via supervision and encouragement from an external body,

integrate full WSP programming into existing water, sanitation, and hygiene programs,

promote community or household-level water treatment and water quality monitoring, and

establish financing and technical assistance to provide communities with permanent solutions to infrastructure deficiencies.

Because all settings are limited by resources to some degree, cost–benefit analysis (CBA) directly comparing the costs and benefits of WSPs represents a critical research need to those considering implementation (Setty, 2019). According to a 2014 survey of 20 private urban water suppliers in China, Cuba, France, Morocco, and Spain, median startup costs for a WSP were €14,050, in addition to 12 full-time-equivalent person-months of internal staff time (Kayser et al., 2019). Annual maintenance costs thereafter were lower, with a median of €1,600 plus 4.7 person-months of internal staff time per year. Data comparing costs to benefits (e.g., increased local business productivity) might encourage hesitant parties to undertake initial investment in WSP development and may clarify the timeline and scale of return on investment. An exemplary CBA in an actual or hypothetical country could establish a replicable method for such comparisons.

Existing literature using CBA as an analytical tool has focused on short-term returns in low- and middle-income countries (String & Lantagne, 2016), which may have inherently greater flexibility in monitoring regimes or poorer initial water efficiency. Settings with an already high regulatory burden, such as the United States (see Amjad et al., 2016), may be less likely to see initial savings from targeting and streamlining risk management programs, where WSPs might add to (rather than replace) existing programs and costs. Legislative flexibility could ease startup by providing water suppliers with multiple options (e.g., to follow default national standards, to customize monitoring parameters and frequency, and/or to shift programming resources to equally protective risk-based alternatives; see WHO, 2018).

In response to the 2020 COVID-19 pandemic, the WHO and UNICEF (2020) advised that survival of the COVID-19 virus in drinking water or sewage is unlikely given current treatment scenarios. These organizations suggested strengthening drinking-water safety by implementing preventive measures to address new risks under the WSP umbrella (e.g., establishing contingency plans for staffing and stocking extra chemicals for water treatment, reagents for water quality monitoring, critical spare parts, and fuel in case of supply chain problems). The impact of the COVID-19 crisis on WSP implementation is a subject of ongoing research. In general, water utilities should revise their WSP to account for the dynamics of the current pandemic and to be fully equipped to respond to future emerging pathogens or other pressing circumstances. Maintaining up-to-date emergency response plans and business continuity plans would help to increase preparedness.

The best risk management programs are those that consider human tendencies and make it easy for people to do the “right thing” (Bartram et al., 2009; Breach, 2012). Water, hygiene, and sanitation improvement initiatives generally cannot take hold and lead to positive changes unless they holistically address and adapt to the needs of the actors who make them possible, including political leaders, government agencies, private companies, public health officials, educators, and consumers. Thus, WSPs blend art and science, integrating the need for audience-specific translation, marketing, and advocacy with awareness of technological advances, research methods, and best practices sourced from around the globe. Although some challenges are common across geographies, all situations have the potential to pose unique challenges, and all plans stand to benefit from multidisciplinary expertise, coordination, and cooperation.


The authors greatly appreciate the efforts of Angella Rinehold (WHO), Andrés Gómez-Lobo (University of Chile), and two anonymous peer reviewers in carefully reviewing and offering suggestions to improve this article.

Further Reading

  • Charles, K. (2015). Water safety plans. In J. Bartram, R. Baum, P. A. Coclanis, D. M. Gute, D. Kay, S. McFadyen, K. Pond, W. Robertson, & M. J. Rouse (Eds.), Routledge handbook of water and health (pp. 245–252). Routledge.
  • World Health Organization (WHO). (2020). Water safety planning resources.