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What are the main sources of faecal contamination of water and how to control them in a water safety plan?

Nov 11, 2021

The water safety plan (WSP) is a methodology to identify and evaluate the hazards and risks associated with the different stages of the water cycle, from the watershed to the consumer. This methodology allows taking care of the water system in an integral way.

The “WHO Guidelines on Drinking Water Quality” recommend water safety plans (WSPs) as the most effective means to systematically ensure the safety and acceptability of a drinking water supply. The WSP approach represents WHO’s health response to Sustainable Development Goal (SDG) 6, aiming to achieve safe drinking water for all.

 WHO/Europe supports the Member States in the region in the implementation of WSPs. Activities range from supporting the development of policies and regulatory frameworks to building the capacities of drinking water providers and public health institutions to introduce and monitor WSPs.

WSPs are based on a comprehensive risk assessment and management approach that covers all stages of water supply, from catchment to consumer. WSPs guide the day-to-day operation of the system and thus ensure the continued reliability and security of the water supply. The principles on which a WSP is based are adaptable to all types and sizes of water supply.

Steps to develop a WSP

• Assemble a multidisciplinary team of local water supply stakeholders to develop and implement the WSP.

• Collect detailed and up-to-date system information, which is verified in the field.

• Systematically identify hazardous events that could affect water safety along the supply chain by introducing chemical, physical, and microbiological risks, including consideration of extreme weather events, accidents, or poor practices (e.g., in agriculture) in the vicinity of the supply.

• Assess the health risks associated with each hazardous event, considering the effectiveness of existing control measures.

• Plan actions and develop an improvement plan to address priority risks that are not adequately controlled, including reviewing control measures, upgrading infrastructure, and improving management procedures. Incremental change is stipulated, as each improvement is prioritized based on public health significance and validated upon completion.

• Prepare management procedures for normal operating conditions and incident situations.

• Establish operational monitoring of control measures to assess their ongoing effectiveness and enable timely corrective action to prevent problems from occurring.

• Verify the effectiveness of the PSA by monitoring and auditing compliance.

• Conduct a periodic review of the PSA to keep it up to date and revise the PSA when necessary, reflecting lessons learned from near misses and unanticipated incidents.


Identify hazards and hazardous events, and risk assessment means identifying all potential biological, physical, and chemical hazards associated with each stage of the drinking water supply system that may affect the safety of the water, contaminating it and compromising its safety, with the consequence of having to interrupt the supply.
At this point, the risks identified at each point of the water flow diagram will be evaluated.

Through field visits and documentation analysis, the WSP team should determine what hazards or hazardous events could occur for each step of the validated process flow diagram.
Determination of hazards also requires evaluation of past information and forecasts based on data from treatment and supply systems.

Risk assessment

The risk associated with each hazard can be described by determining the likelihood of its probability of occurrence (e.g., “certain”, “possible” or “exceptional”) and assessing the probability of an event (e.g., “certain”, “possible” or “exceptional”).
The consequences should they occur (e.g., “negligible,” “severe,” or “catastrophic”).

The most important consideration is the potential impact on public health, but other factors, such as organoleptic effects, may also be considered.
It is essential to define beforehand the risk matrix score that determines whether a risk is classified as “significant”. The information on which the risk assessment will be based will be derived from experience, knowledge, and judgment of each of the team members of the water utility, industry best practices and technical literature, a good understanding of the water supply company, and each of the water supply companies.
The risk assessment should be specific to each drinking water supply system because each system is unique.

Typical hazards affecting water catchments include microbiological hazards, which we specialize in at Bluephage.
Agriculture, industry (including former industrial sites, brownfields, and abandoned industries), water pits, domestic septic tanks, slaughterhouses, animals, and various recreational uses of water by people are the primary sources of faecal water contamination.

Bluephage’s team of experts offers consulting services to implement Water Safety Plans and monitor faecal water contamination through its Easy Kit and Rapid Kit, streamlining and drastically reducing the preparation time for obtaining results. In addition, the monitoring can be adapted to the risk assessments estimated in the Water Safety Plan, and the Bluephage team can suggest various water treatments if few infections are found, such as filtration or water chlorination.

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