Safe management of drinking water supplies

With the 2003 edition of the Guidelines for Drinking-water Quality, GDWQ, the WHO recommended a comprehensive risk assessment and risk management approach for the first time, termed Water Safety Plans. With this approach, risks to human health can be systematically identified, assessed and controlled in all processes from catchment to consumer.

WSP is a preventive management system tailored towards water supplies. This approach can be universally applied, irrespective of the type of raw water source used, the size or the complexity of the water supply.

For practical implementation of the WSP-approach, WHO has developed a number of tools, including for example a manual for large water supplies as well as a manual and a field guide for implementation in small community water supplies.

At the European level, the WSP-approach was first taken up through the DIN-EN 15975-2 in 2013. UBA, together with the Water Technology Centre (TZW), developed a manual for implementation of the WSP approach in small-scale water supplies in Germany. The manual complements the DIN-EN 15975-2 with practical explanations, recommendations, examples and supporting tools. The revised Drinking Water Ordinance (TrinkwV) and the new Ordinance on drinking water catchment areas (TrinkwEGV), both of 2023, established legal requirements for risk management, both in catchment areas for abstraction points of water intended for human consumption, as well as in water supply systems, in Germany.

Developing a risk management can help to identify and remediate weaknesses of the system. The process substantially improves the understanding of the specific water supply system and thus strengthens due diligence and organizational confidence of the water supplying entity. Applying risk management also improves the knowledge of the locally relevant technical rules and their application, and it provides a technically sound basis for decisions on improvements. Risk management also improve communication between stakeholders within the water supply, as well as with external stakeholders, particularly competent authorities.

The risk management approach comprises hazard analysis, risk assessment and systematic process control. It is an operational quality management concept which includes the following steps:

1. The first step of the risk management approach is for senior management of the water supply to assemble a team. The team is responsible for independently developing a risk management and for implementing it in routine operation of the supply. A committed team which is capable of acting and which encompasses the expertise required for a comprehensive risk assessment is presented is a prerequisite for successful risk management implementation. Both the TrinkwV and the TrinkwEGV require basic technical knowledge of the persons that are implementing the risk management.
2. The description of the water supply system is the basis of every risk management. It has to cover the catchment area, abstraction, treatment, storage and the distribution system, including pumping stations and pressure boosting systems.
3. The system assessment consists of a hazard analysis and a risk assessment. In WSP terminology, a hazard is any biological, chemical, physical or radiological agent in the water supply system which may cause harm to public health. Hazardous events in the risk management context are incidents or situations which cause hazards to occur in the drinking-water supply. As part of the risk assessment, the team evaluates the risk caused by every hazardous event identified. The risk comprises the two aspects of likelihood to occur and potential severity of consequences. The intention of the risk assessment is to compare and prioritise the hazardous events within a water supply according to their risk levels.
4. Measures for controlling the risks ensure drinking-water quality and reliability of the water supply. Such measures include all actions, activities and processes which aim at permanently eliminating or reducing risks. In this step, the team should also check and confirm to what extent the existing measures actually control the risks. This means to answer the question: "Is the chosen measure suitable and effective?" for each measure identified. Should this validation process show that the already existing measures are not sufficient to control the identified risk, action for improvement or upgrade needs to be taken, and the team should change, optimise, complement or replace the measures respectively. If the validation even indicates that measures are absent, the team should identify and implement suitable technical, organisational or staffing measures.
5. The operational monitoring programme comprises regular planned inspections, controls or measurements of selected parameters. It aims at ensuring that the control measures in place have been implemented and are operating effectively as planned. Operational monitoring is NOT the same as testing the ‘end product’ drinking-water in accordance with the requirements of the TrinkwV, but rather includes parameters which can be easily measured or observed according to § 30 TrinkwV, and for which the measurement results are, if ever possible, instantly available. Its purpose is to show that a measure is working within its operational limits (e.g. turbidity at a filter effluent).
6. Verification is an integral part of a risk management in order to confirm that the limit values and requirements of the TrinkwV, as well as water supply goals, are attained.  Classical end product testing of drinking-water in terms of regular self-control by the water supply utility when the water leaves the waterworks and within the distribution system is verification. 
7. It is important that the team documents the results of each risk management step, as well as the underlying considerations. Further information on documentation can be found in the guidance for the TrinkwEGV (LAWA Vollzugshilfe zur Umsetzung der Trinkwassereinzugsgebieteverordnung – TrinkwEGV ) as well as in the draft recommendation on documentating risk management for division 7 of the TrinkwV Entwurf der Vorgaben zur Dokumentation des Risikomanagements gemäß Abschnitt 7 TrinkwV.
8. A risk management is never "completed", but should rather be continually and regularly updated and improved by the team. The aim of this planned, periodic review is to "step back to see the bigger picture" to confirm the validity of the risk management.

The German TrinkwV and TrinkwEGV require that the risk management needs to be conducted at minimum in compliance with the generally acknowledged technical rules and standards.

In total, approximately 300 technical rules describe what needs to be considered in drinking-water supply – for all steps in the process from establishing drinking-water protection zones to testing water taps for their certification. The DVGW has compiled a selection of technical rules particularly for the operation of small-scale water supplies. The aim of the Technical Safety Management (TSM) of DVGW is to support water suppliers in meeting their responsibilities and to strengthen their technical self-management.

The DIN-EN 15975-2 of the DVGW describes central elements of the risk management under normal operating conditions, integrating it into the set of technical rules, whereas the DIN-EN 15975-1 deals with emergency conditions. The technical standard DVGW W 1001 complements information on risk management and emergency response for the national level.
 

The German Environment Agency has completed several projects with partners from water supplies, health agencies and operators of buildings in order to assess the extent to which the risk management approach can be implemented in large and in small-scale water supplies, as well as in buildings in Germany, which prerequisites and potentially support is required, and which benefits it conveys. Currently, UBA is conducting a project on integrating the effects of climate change in the risk management approach. It has developed training materials, which are available free of charge, explanatory videos, as well as an e-learning course for local health agencies. 

In its capacity as a WHO Collaborating Centre for Research on Drinking-Water Hygiene, UBA also provides consulting services to stakeholders in other countries on implementing the WSP approach, and it supports the development of training materials, tools and guidance for implementing WSP.