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Water Safety Plans (WSPs)

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The World Health Organization (WHO, 2008) Guidelines for Drinking Water Quality (GDWQ) is the basis for current water quality standards in many countries around the world. In the GDWQ, Water Safety Plans (WSPs) are described collectively as a systematic and integrated approach to water supply management based on assessment and control of various factors that pose a threat to the safety of drinking water. WSPs enable identification of threats to water safety during any and all steps in the catchment, transport, treatment and distribution of drinking water. This approach is fundamentally different from those traditionally adopted by water suppliers, which rely on treatment and end-product testing to ensure water safety. When implemented successfully, the WSP approach can ensure that water quality is maintained in almost any context.

Description: 

Chapter 4 of the GDWQ describes a framework for preventative management and delivery of safe drinkingwater. This framework is illustrated in figure 1. Though the specific inputs and outputs of WSPs may vary from case to case, the basic components remain the same regardless of the context. As shown in the figure, a WSP consists of three separate activities: system assessment, monitoring and management.

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Figure 1: Framework for safe drinking water (source: WHO, 2008)

System assessment: During this phase of a WSP, potential hazards to water quality and health are identified at key steps or locations, normally referred to as Critical Control Points (CCPs), within specified boundaries of a water supply chain. Typical health hazards might be source catchment contamination, poorly maintained service reservoirs, leaking valve boxes or unhygienic standpipe collection systems (Godfrey and Howard, 2004). Associated risks of negative health outcomes due to these hazards are also quantified at this time.

Monitoring: Once health risks have been defined, they are used to develop a prioritized and system-specific plan for monitoring and controlling hazards at each CCP during the monitoring phase of a WSP. Such a plan will define operational parameters and associated sampling and reporting methods. Critical limits or targets for these parameters should be defined at this time. It is likely that a combination of observational and traditional water quality monitoring methods will be implemented by members of the community as well as by trained personnel.

Management: The actions necessary to correct any issue identified during monitoring are established in the management phase of a WSP. Such measures may include alleviation of source water contamination through controlling activities in the watershed, optimization of physical or chemical treatment processes, and prevention of recontamination during distribution, storage and handling (Water Safety Plans, 2010). By controlling hazards at the water supply system’s CCPs, any issue that occurs in the catchment or distribution network can be detected and corrected before water of poor quality is delivered to the consumer. This proactive method of monitoring reduces the amount of sampling that needs to be conducted in the distribution system. In addition, processes are established for documentation and record keeping, and validation and verification during the management phase.

The WHO has published a foundational document that describes the process water suppliers must follow in order to ensure that a WSP is planned and implemented properly (Davison et al., 2005). These steps are illustrated in Figure 2 and have been summarized as follows (Godfrey and Howard, 2004). In order to develop a WSP, a water supplier must:

  • Assemble a team that understands the water supply system and its capability to meet the water quality targets
  • Identify where contamination could arise within the water supply, and how it could be controlled
  • Validate the methods employed to control hazards
  • Establish both a monitoring system to check that safe water is consistently supplied and agree to corrective actions in the case of deviation outside acceptable limits
  • Periodically verify that the WSP is being implemented correctly and is achieving the performance required to meet the water safety targets

illustration © climatetechwiki.org

Figure 2: Steps in the development of a WSP (adapted from Davison et al., 2005)

Advantages of the technology top

The Intergovernmental Panel on Climate Change predicts that climate change will lead to, among other things, increased global temperatures, flooding events and periods of drought as well reduced freshwater resources and sea level rise (IPCC, 2007). These changes are projected to have many adverse impacts worldwide drinking water resources: cyanobacterial activity will increase within water bodies; the frequency of physical and chemical contamination of water bodies will increase; harmful nutrients and other pollutants will become concentrated in water sources; unprotected sources will be used at increasing rates; and saline intrusion will occur in coastal rivers and groundwater sources. Any hazard that occurs as a result of climate change will lead to increased health risks in the water supply chain and will have implications on water safety.

WSPs contribute to climate change adaptation at the catchment level primarily through increased resilience to water quality degradation. The WSP approach allows for water suppliers to be flexible and responsive to changing input parameters. This means that the monitoring, management and feedback components of a successful WSP naturally absorb the acute impacts of climate change. The WSP approach can also be modified to adapt to long-term climate change and slow-onset hazards by recognizing how the water supply system may be affected by specific climate change effects, by factoring these effects into the risk assessment, and by identifying appropriate control measures.

The burden of disease attributable to poor water, sanitation and hygiene has been estimated to be over 200 times higher in developing than in developed regions (Prüss et al., 2002). Waterborne illnesses diminish economic productivity and confine people to poverty. Since WSPs are developed to meet health-based targets that are specific to the disease burden of a particular region, the approach can significantly reduce the risk of exposure to health hazards that contribute the most to disease in developing countries (Davison et al., 2005). Therefore, WSPs can make a significant contribution to economic development by reducing the burden of waterborne illness in resource-limited settings.

Financial requirements and costs top

The implementation of a WSP will potentially require water suppliers to increase sampling frequency and number of locations where process indicators (such as turbidity, chlorine, residuals, pH, etc.) are monitored. However, the amount of required microbiological tests will also decrease significantly. In fact, it is likely that the cost of providing and distributing safe water from a risk-based approach will actually be less than from a traditional end-product monitoring approach (Davison et al., 2005). This is especially true in developing countries, where consumables required for coliform and other microbiological testing are expensive and where a high percentage of monitoring funds are spent on field test kits or maintaining expensive certified laboratories. Even in cases where the equipment required for on-line monitoring must be purchased, the recurrent cost savings of using process indicators for monitoring instead of microbiological indicators is almost certain to outweigh the initial capital investment.

The WSP approach can also result in long-term decreased institutional costs. In general, the planning process identifies opportunities for low-cost improvements on operations and management practices. However, WSPs also improve the efficiency of communication and collaboration between water providers, consumers, regulatory authorities and the commercial, environmental and health sectors. This creates an enabling environment where financial support can be leveraged and where capital improvement needs can be prioritized and sustained (PAHO et al., 2010).

Institutional and organisational requirements top

The WSP design team must have a sound understanding of the catchment area, treatment facilities, and distribution networks that make up a water supply system. These components must be mapped and characterized in order for the system’s capability to meet water quality targets to be fully understood and for control measures to be developed. This may require in-depth assessment of the water supply chain, as some information may be unknown prior to development of the WSP.

It is also important that WSP designers and stakeholders understand how water quality affects health in order for appropriate limits on specific water quality parameters to be set. This requires basic knowledge of sampling and monitoring techniques as described in the GDWQ. Furthermore, the members of the design team must have a working knowledge of the corrective actions that should be taken when water quality deviates outside acceptable limits.

A number of stakeholders are usually involved in various aspects of the water supply chain. Therefore, the WSP design team must understand how the implementation of a WSP will affect pre-existing water sector arrangements. Understanding such arrangements will allow WSP designers to facilitate cooperation among all stakeholders. This may require a review of the current organizational and institutional structure in order to establish which entities have a vested interest in or responsibility for water safety. The process for conducting an in-depth review of sector arrangements is available in the references (Godfrey and Howard, 2004).

The institutional and organizational requirements of a WSP are related primarily to personnel needs. The first step in planning a WSP is to set-up a steering group that is composed of members from varied professional backgrounds. This interdisciplinary team will be responsible for gathering the background information required to plan a WSP and for developing its components. The steering group should include engineers, water quality managers, academics, planners, surveyors, sociologists and health scientists (Godfrey and Howard, 2004). In addition to the steering group, it should be made clear which entities or individuals are responsible for carrying-out operational monitoring, for documenting and reporting monitoring results, for taking corrective action when necessary, for performing operational audits, and for certifying and validating the risk assessment plan.

In order for the implementation of a WSP to be successful, it is also important that all stakeholders buy into the process. While representation of all stakeholder entities on the steering group will help to encourage cooperation, some cases may require additional effort from WSP designers to foster an environment of acceptance and trust. Strategies for ensuring commitment from all levels of water sector involvement have been published in the literature (Godfrey and Howard, 2004; Davison et al., 2005).

Barriers to implementation top

The primary barrier to implementation of WSPs is that certain stakeholders may be hesitant to adopt such a fundamentally different paradigm for water supply management. Additionally, a number of barriers to the implementation of WSPs that are specific to developing countries have been reported (Godfrey and Howard, 2004). These include, among others:

  • Limited data availability
  • Unplanned development
  • Lack of sanitation infrastructure
  • Limited system knowledge
  • Limited equipment/human resource availability

Theoretically, a WSP can be put into practice at any time for a water supply of any size. In reality, small, community-managed water supply systems face a number of unique barriers to planning and implementing WSPs. In such systems, technologies may range in sophistication from a single borehole or tubewell fitted with a handpump to complex treatment schemes, and operation and maintenance is performed by members of the community with limited specialist skills. In most cases, the management personnel can commit only a limited amount of time to running the system and overseeing its operation, and they receive little or no formal training or financial compensation. They are often forced to rely significantly on local or national government for general support and guidance. Furthermore, it is likely that managers of such water supply systems will have limited access to proper water quality testing and construction equipment. Ways that managers of small, community-managed water supply systems can overcome these limitations in planning and implementing WSPs are addressed in chapter 13 of “Water Safety Plans: Managing drinking-water quality from catchment to consumer” (Davison et al., 2005).

It is often very difficult to characterize water supply systems in developing countries. Limited development regulations have resulted in unplanned expansion of water and sewer networks. The fact that current and accurate network maps are rarely available makes it difficult to locate supply mains, and system analysis may then rely heavily on local knowledge. The matter is exacerbated by the fact that cross contamination of water pipes is common due to poor access to urban sanitation, and the lack of available resources limits the extent to which water suppliers are able to maintain adequate operation and maintenance. 

Opportunities for implementation top

Opportunities for WSP implementation arise whenever the supplier is motivated to pursue a risk-based approach and when the personnel capacity exists to make the necessary changes. Although there are many challenges for implementing WSPs in developing countries, the approach enables a much more holistic and robust assessment of threats to drinking water safety than conventional approaches focusing on end-product testing.

References top

Davison, A., G. Howard, M. Stevens, P. Callan, L. Fewtrell, D. Deere, J. Bartram. (2005). Water Safety Plans: Managing drinking-water quality from catchment to consumer. World Health Organization. Geneva. Available online at http://www.who.int/water_sanitation_health/dwq/wsp0506/en/index.html Accessed 25 November 2010.

Godfrey, S. and G. Howard. (2004). Water Safety Plans for Urban Piped Water Supplies in Developing Countries. WEDC, Loughborough University, UK. Available online at http://www.bvsde.paho.org/CD-GDWQ/CasosEstudiosPSA/WSPDevelopingCountrie... Accessed 29 November 2010.

IPCC (2007) Climate Change 2007: Impacts, Adaptation, and Vulnerability.

Pan American Health Organization (PAHO), U.S. Center for Disease Control and Prevention (CDC) and United States Environmental Protection Agency (EPA) (2010) Latin America and Caribbean Water Safety Plan Network. Available online at http://www.bvsde.paho.org/bvsacg/red_lac_psa/documentostecnicos/doctecen... Accessed 26 November 2010.

Prüss, A., D. Kay, L. Fewtrell, J. Bartram. (2002). Estimating the burden of disease from water, sanitation and hygiene at a global level. Environ Health Perspect. 110(5):537–542. Available online at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1240845/ Accessed 29 November 2010.

Water Safety Plans. (2010) U.S. Center for Disease Control and Prevention. Available online at http://www.cdc.gov/nceh/ehs/gwash/wsp.htm Accessed 26 November 2010.

World Health Organization (WHO). (2008). Guidelines for drinking-water quality. Third Ed. Geneva, Switzerland: WHO. Available online at http://www.who.int/water_sanitation_health/dwq/gdwq3rev/en/ Accessed 28 November 2010.