1. Importance of the risk assessment/risk management approach

Drinking water is monitored to ensure that it is safe and of adequate quality, as the final product of the production chain. Monitoring this final product has been the norm and standard practice in order to assess whether it is of sufficient quality. However, risks might be detected too late, or are possibly not detected at all. This has consequences for public health. For this reason, risk based approaches for the drinking water supply system as a whole have come into being (Van den Berg et al., 2019).

This change in paradigm is closely related to the emergence of the concept of “due diligence”. The concept means the prevention of foreseeable harm at reasonable cost. “Demonstration of due diligence requires showing that all reasonable measures have been taken in advance to prevent the occurrence of negative health consequences” (Medema et al., 2003, 23, Figure 2). When an effect is identified that could possibly have an adverse effect, an approach should be used that is precautionary and assesses and manages the risks.

Figure 2

The goal of a risk management approach is to assure safe drinking water. Hrudey et al. (2006) point the attention to the need to consider what is safe. They argue that the concept of safety has impeded the debates about risk management for years, and propose a notion of safety as “a level of risk so negligible that a reasonable, well-informed individual need not be concerned about it, nor find any rational basis to change his/her behaviour to avoid such a small, but non-zero risk. [....] In the context of drinking water, and given our current capability for reducing risks, this notion of safe drinking water should mean that we do not expect to die or become seriously ill from drinking or using it.” (Hrudey et al., 2006, 3).

Hrudey et al. (2006, 3) define four characteristics of risk management for safe drinking water, as described by the Walkerton Inquiry:

• “Being preventive rather than reactive.
• Distinguishing greater risks from lesser ones and dealing first with the former.
• Taking time to learn from experience; and
• Investing resources in risk management that are proportional to the danger posed.” (Hrudey et al., 2006, 3).

Hazard Analysis Critical Control Point (HACCP) is an example of a RA/RM approach. The HACCP approach came into being in the 1990s through the projects of Pillsbury Company in their research on food production for the US space program. The principles and approach of HACCP have since been applied in the food sector for food safety management. HACCP is based on three principles: understanding the system, prioritizing the risks, and establishing control measures to reduce the risks. In 1994, Havelaar investigated the use of HACCP for drinking water supply systems. Back then, some countries already required a HACCP approach, since water supply was regulated through regulations for food protection. A number of utility companies started to apply the HACCP principles. The ‘Catchment to consumer’ approach to risk management, as illustrated below, is based on the HACCP principles (Fewtrell and Bartram, 2001).

A group of experts started to investigate the potential to create more coherence between risk assessment and -management approaches for water-related microbial hazards. This has led to the Stockholm Framework, which further examined the use and value of HACCP for drinking water supplies (Fewtrell and Bartram, 2001). Consequently, the ‘Framework for Safe Drinking-water’ was defined in the third edition of the WHO Guidelines for Drinking Water Quality. This included the setting of health-based targets, an RA/RM approach and independent surveillance (van den Berg et al., 2019) This RA/RM approach was coined the Water Safety Plan (WSP).

2. The Water Safety Plan

The main starting point for the setting of water quality standards worldwide are the World Health Organization Guidelines. The Guidelines for Drinking-water Quality (GDWQ) is one of the three guidelines concerned with water quality. All three have the main aim of improving health. An instrument that is promoted in this context is the Water Safety Plan (WSP).

Figure 3

The WSP is a step-wise approach to ensure the safety of drinking water. It is a comprehensive risk assessment and risk management approach, that covers all steps in the water supply. The goal of a WSP is to ensure, through good water supply practice, that drinking water is safe. This means:

• “to prevent contamination of source waters;
• to treat the water to reduce or remove contamination that could be present to the extent necessary to meet the water quality targets; and
• to prevent re-contamination during storage, distribution and handling of drinking-water.” (Davison et al., 2005, 11, Figure 3).

These objectives apply to all kinds of water supplies, regardless the size or complexity (Drinking Water Inspectorate, 2005). A WSP has three components:

• System assessment: The WSP team identifies the potential hazards, the level of risk these potential hazards pose, and the control measures that can ensure that the water supply is safe.
• Operational monitoring: monitoring of the control measures.
• Documentation of management arrangements: Documentation of the system assessment, operational monitoring, management procedures, supporting programmes etc. These three components are divided in eleven steps, from assembling the team to revising the WSP, as can be seen in Box 1. This report focuses on steps three and four.

An important element of the WSP approach is that it combines both content and process. On the content side, it is about describing the water supply system, assessing hazards and risks and determining measures. But of similar importance is the status of the WSP and its place in the organization, the mandate of the team, the budget and management commitment. This management commitment is essential for a WSP to be succesfull (Drinking Water Inspectorate, 2005).

It is important that the WSP and the approach is embedded within the organization, and is part of the operating/management procedures rather than being a one-time activity. The WSP has two unique characteristics. The WHO (2011) argues that it is easily adaptable to different socioeconomic systems, and it can be effectively applied at different levels and scales.

3. Small and large water supply systems

Often a distinction is made between small and large water supply systems. However, the definitions used to describe small- and large-scale supply systems differ widely between (and even within) countries. Often, the characterization of the supply is based on specific criteria like population size, type of supply technology, quantity of water supplied, size of the supply area etc. This FAIRWAY report however distinguishes between small and large water supply systems because of their characteristics that affect Water Safety Plan implementation. Small supplies face challenges in setting up and implementing a WSP. These challenges relate to administration, management, operation and the regulatory context (WHO, 2011). It is those challenges that set small systems distinctly apart from large supplies, and thus define them in this context. Box 2 describes the challenges typically faced by small water supplies.

During a FAIRWAY field visit very small drinking water supplies were examined in Romania. In Figure 4, a Roma family and their small (private) drinking water well can be seen. These wells are mostly 10-20 m depth, in the first aquifer below a shallow clay layer on top.

In the recap of the Drinking Water Directive there is special attention to vulnerable groups in society and their access to water intended for human consumption. Member States are asked to pay specific attention to vulnerable and marginalised groups, such as refugees, nomadic communities, homeless people and minority cultures such as Roma and Travellers, whether sedentary or not. Examples of measures to improve access that are mentioned in the recap of the DWD are providing alternative supply systems, such as individual treatment devices, providing water through the use of tankers, such as truck and cisterns, and ensuring the necessary infrastructure for camps.

Figure 4

Examples of Water Safety Plans, both of large and small supplies, can be found in »Annexes 1 and 2 respectively. Annex 1 provides an example of a Water Safety Plan for a Dutch public drinking water supply. It shows the following elements of the WSP: description of the water system and the surroundings, water quality and quantity, land use of recharge area, risks and relevant developments, and remaining problems/tasks. Annex 2 provides an example of a Water Safety Plan for a small supply in the Netherlands. The factsheet is made for small-scale abstraction sites, which include water supplies for drinking water consumption other than those for public drinking water supply. These are mainly privately owned groundwater abstractions used by third parties as drinking water (e.g. campsites and holiday parks) as well as industrial sites, that abstract groundwater for food production.

Notes:

For full references to papers quoted in this article see »References

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