Ensuring safe drinking water: converting commitment into action and foresight

20 years have passed since the World Health Organization (WHO) published its third edition of Guidelines for Drinking-water Quality (WHO 2004), a major advance in the guidance for water-providers to ensure safe drinking water. This advance was the product of more than a decade of international discussion about how to better prevent contamination of drinking water by adopting a preventive risk management approach. The prevailing perspectives about ensuring safe drinking water in the 1990s had been dominated by a primary focus on setting and meeting quantitative limits for an expanding list of water contaminants monitored in finished drinking water. This approach is inherently reactive rather than preventive because treated water monitoring is not continuous for most contaminants and results are normally not available until after the drinking water has been consumed. Drinking water guidelines needed to be restructured to provide a fundamentally preventive risk management approach developed to achieve health-based targets. Those guidelines also needed to establish a more realistic balance for microbial pathogens versus chemical contaminants. That balance needed to recognize the substantial and certain evidence that pathogens in drinking water cause adverse human health outcomes versus the much more uncertain evidence for most chemical contaminants. The latter mainly warrant control from a precautionary public health perspective rather than the certain drinking water health risks of pathogens confirmed by experience.

An early influential proposal to improve the capability of drinking water guidelines was provided by Havelaar (1994) suggesting a risk management approach for drinking water guidelines modeled on what had been adopted internationally for food safety. This approach was pursued by some European nations (e.g., Iceland, Switzerland). Dr. Jamie Bartram, in charge of the WHO drinking water guidelines program sought adoption of a risk management approach and led a major international effort to address improvements that was addressed by a 1999 expert meeting in Stockholm where foundational concepts for water safety plans (WSPs) were developed (Bartram et al. 2001; Deere et al. 2001). Meanwhile, Australia was also pursuing a risk and total quality management-oriented restructuring of its national drinking water guidelines after the 1998 ‘Sydney Water Crisis’ (Clancy 2000) by means of a working group established by the Australian National Health and Medical Research Council (NHMRC) from 1999 to 2002 (Rizak et al. 2003). These parallel initiatives led to a week-long joint meeting of the WHO expert group with the NHMRC working group in Adelaide in May 2001 to compare their respective risk management approaches. These activities also led the founders of the Global Water Research Coalition (https://globalwaterresearchcoalition.net) to initiate the creation of the Bonn Network that resulted in the 2004 Bonn Charter for Safe Drinking Water (IWA 2004) and an international conference in Berlin in April 2003 (Schmoll & Chorus 2003) that elaborated on and promoted a risk management approach to ensuring safe drinking water. Ultimately, these risk management initiatives became official with the publication of the third edition of the WHO Guidelines for Drinking-water Quality (WHO 2004) that formally introduced the concept of WSPs and the Australian Drinking Water Guidelines (NHMRC 2004) that were fundamentally restructured to incorporate a Framework for Management of Drinking Water Quality.

WHO and IWA sponsored and launched an online resource to provide access to resources in support of water safety planning (https://wsportal.org). Major documentation about the objectives and means to implement WSPs effectively was published (Davison et al. 2005; Howard & Schmoll 2006) and the first edition of the WHO Water Safety Plan manual (Bartram et al. 2009) was introduced at an IWA–WHO Conference on Water Safety Plans – Global Experiences and Future Trends in Lisbon in May 2008. Experience and insights about water safety planning were captured by Breach (2012) and guidance for WSPs for small drinking water supplies was published (WHO 2012). Rickert et al. (2016) provided an overview of how risks for surface water supplies can be assessed and managed with WSPs.

A little more than a decade after the formal publication of the WSP concept in 2004, WHO (2017) published a survey reporting that 93 countries in every region of the world had adopted WSPs at least to some degree of implementation. IWA sponsored another water safety conference in Narvik, Norway in June 2022 (IWA 2022). The second enlarged edition of the WHO Water Safety Plan Manual (Jackson et al. 2023) with contributions from 83 water professionals from 35 nations was published in 2023. With this recent background the Journal of Water & Health solicited submissions for a special issue to address research and experience with drinking WSPs published on the 20th anniversary of the WHO Guidelines for Drinking-water Quality (WHO 2004) and the Australian Drinking Water Guidelines (NHMRC 2004) that proposed this preventive risk management approach for ensuring safe drinking water.

This compendium contains 16 contributions covering a wide range of issues arising from practical experience with WSPs from 20 different nations. The following papers address different stages and aspects of implementing WSPs including important challenges that must be addressed.

Successful implementation of WSPs requires a supportive enabling environment. Several aspects of a supportive environment are highlighted by specific examples included in this special edition. Firstly, a regulatory mandate is an important driver of WSPs implementation. Uruguay has embarked on an ambitious program for nationwide adoption of WSPs by 2030. As of 2022, WSPs had been implemented in 94 of 570 water supply systems. Vieira et al. (2023) report on the institutional arrangements and specific conditions of the national regulatory framework intended to support upscaling of WSPs implementation.

Successful implementation and sustainability of WSPs requires ongoing auditing. In Hungary, WSPs are subject to a two-stage regulatory audit, a consultative central technical audit and a formal local audit. Bufa-Dõrr et al. (2023) report on a review of the audit experiences of over 1,200 WSPs and noted that implementation of WSPs has been a learning experience with both WSPs and auditing reports improving over time. The efficacy of auditing procedures is a recurring theme for effective WSPs.

In addition to regulatory requirements, it is critical to ensure that regional systems and smaller utilities have access to the skills and resources necessary. This need was explored through semi-structured interviews with 53 stakeholders by Gunnarsdottir et al. (2023) in the context of small water supplies in eight Nordic countries (Denmark, Finland, Iceland, Norway, Sweden and three self-governing nations: the Faroe Islands, Greenland and Åland). The authors argue that in addition to an obligatory regulatory mandate for WSPs, successful implementation will require provision of specialized technical support through training, guidance with using water monitoring data, development of simple risk assessment guidelines and increasing cooperation in the water sector, especially through professional associations.

Huynh et al. (2023) report on the support provided to regional communities and small utilities in the Australian state of New South Wales (NSW) led by the water quality regulator (NSW Health). Through a partnership approach in place since 2010, NSW Health have helped assess water quality risks and informed the development of new infrastructure funding programs, the development of a formal audit program and facilitated better government collaboration. Designing a monitoring system to assess the effectiveness of a program is good practice; NSW Health used standardized pre- and post-project surveys to assess the impact of the provided support. Their paper details the nature of the support that has been provided and includes a discussion of the statistically significant improvements across many elements of drinking water management systems in NSW. The authors argue that ongoing support is needed to overcome financial and resource constraints of small and regional utilities.

In Serbia, small regional communities have limited human, financial and administrative resources for implementation of WSPs, a situation common to many global contexts as outlined by van den Berg et al. (2023). They describe a novel approach of integrated implementation of water and sanitation safety planning systems, harnessing the technical support needed for both processes within the one framework. The integrated approach is consistent with a holistic view of water systems where drinking water and sanitation systems are interrelated, and is pragmatic in the use of technical resources.

In some contexts, the need for the risk-based approach of WSPs is still being demonstrated. Olalemi et al. (2023) describe their experience for small groundwater supply systems in Nigeria that evaluated correlations of enteric bacteria monitoring with hazard identification achieved by sanitary inspection. The study showed that the water quality was generally poor, but also identified priorities for action, including potential control measures to improve water safety and help in defining critical limits. The authors argued that given the limited predictive power of Escherichia coli detections in their context, their initial QMRA may provide a more robust basis for protective health-based water quality targets.

In the spirit of collaboration recommended by several papers in this volume, Sheehan et al. (2023) report on a peer-to-peer partnership between the Ghana Water Company Limited (GWCL) and two water utilities (Yarra Valley Water and Coliban Water) based in the Australian state of Victoria. The partnership was initiated through WHO and IWA with support provided by UNICEF, with the intent of sharing operational experience on the day-to-day management of water treatment plants within a WSP.

International collaboration needs to also consider the local cultural context carefully. Souter et al. (2024) report on the needs of the Pacific Island communities where there is limited capacity to facilitate and participate in the development of WSPs. The identified major challenges to implementing WSPs included weak and inactive water committees and teams, leading to reduced implementation and low community interest to act upon the plans. The researchers report on the importance of ensuring WSPs are appropriate to the local context. Adapting teaching methods to align with culturally specific learning styles and literacy levels is necessary to support effective WSP implementation.

Water suppliers in New Zealand have been preparing WSPs since 2005, yet outbreaks of campylobacterosis occurred in Darfield in 2012 and a large, fatal outbreak in Havelock North in 2016. Graham et al. (2023) report on why the WSPs in place failed to prevent these outbreaks. Specific limitations of seriously underestimating public health risks and overestimating the security of groundwater were identified despite available and relevant evidence about the risks. However, an overarching issue was a misguided focus on narrow regulatory compliance rather than using WSPs as a tool to proactively understand and effectively manage public health risks.

Highlighting a similar problem, Fuller et al. (2023) report on the progress of water quality management in Ontario, Canada since the fatal Walkerton tragedy in 2000 (O'Connor 2002) and discuss alignment of the Ontario's Drinking Water Management Standard that was guided by the Australian Drinking Water Guidelines and the WSPs quality management frameworks. While they report strong alignment, the authors argue that existing performance data were strongly focussed on regulatory outcomes. There is a need to develop mechanisms to ensure continual improvement of the Drinking Water Quality Management Standard (DWQMS) because a preventive risk management approach must be able to reflect upon and learn from previous failures.

Noting the need to focus on continual improvement, Jayaratne et al. (2023) report on the ongoing lessons learned through recent challenging scenarios in Melbourne, Australia. The water utilities servicing Melbourne were early adopters of the WSP approach and have demonstrated organizational maturity in their implementation. Nevertheless, through recent challenging experiences, the authors show the need for ongoing risk reduction strategies, continuous improvement and effective auditing procedures to ensure continuing vigilance and protection of public health.

A key aspect of the risk management approach of WSPs is assessing the risk associated with hazardous events that can occur in a drinking water system. Lane & Hrudey (2023) critically analyzed the structure of risk matrices for WSP risk assessments for 12 international jurisdictions and found that all but one violated statistical foundations for accurate risk ranking. The identified flaws allowed for latent risks to be underestimated, with the subsequent potential for unmanaged risk and catastrophic failure. They argue that improving risk matrix structure could be achieved by setting clearer risk level boundary criteria, aligning specific impact category definitions with water system objectives, and selecting specific impact categories.

The risk assessment process within WSPs has inherent dangers of underestimating the magnitude of public health risks. As evidenced in New Zealand, such misdiagnosis can be catastrophic (Graham et al. 2023). Walker (2023) explores this concern in the context of latent risks associated with water supplies in the state of Western Australia and argues that likelihood assessment needs to be undertaken within the context of a multi-barrier approach. Where adequate and reliable multiple barriers to contamination are present and fully functional, the likelihood of a hazardous event should be categorized as rare. When barriers are inadequate or unreliable, then a higher likelihood of failure is appropriate. Absence of any barriers to contamination should not be tolerated by arguing that disaster has apparently not yet happened. This barrier assessment should inform the operational monitoring program, enabling regular confirmation of the barrier performance.

As natural hazardous events increase in magnitude and frequency, there is need to further develop approaches for including the assessment and management of such events within the WSPs. Three papers specifically address this need:

• Amadio et al. (2024) reviewed the implementation of 168 water utilities' WSPs in six countries: Italy, Slovenia, Croatia, Serbia, Montenegro, and Greece. The authors present a framework for multi-hazard risk assessment that is integrated into the WSPs. The researchers identified practical goals to enhance water utilities resilience to natural hazardous events through water safety planning. These included interoperability of different databases, the development and implementation models simulating impacts over time that are shared among stakeholders and developing national and transnational registries of impact from natural hazardous events on the water supply system.

• Biasibetti et al. (2024) developed risk matrices that specifically address climate-related catchment risks to groundwater and surface water (lakes and rivers) sources including estimates of probabilities. Residual risks were addressed by potential mitigation measures including emergency response plans and the use of alternate water sources, storage, and interconnection with other water distribution networks.

• Krause et al. (2024) describe a program to support water safety planning for German healthcare facilities to address extreme events. The program found that the unique challenges of providing safe water supplies for healthcare facilities are affected as much by social as by technical considerations, including a lack of awareness about the vulnerability of healthcare facilities to an impaired water supply. These factors provide obstacles to taking appropriate preventive actions.

This compendium brings together a diverse range of authentic accounts examining the successes and challenges with the development and implementation of WSPs from small rural systems to large cities from both low and high income countries. The value of WSPs is evident in providing a ‘know your own system approach’, knowing the threats and challenges it faces and its capabilities for effectively managing identifiable risks. However, it is also clear that ensuring that WSPs can deliver on their potential is not guaranteed. The authentic experience documented in this selection of papers offers readers a window on many of the challenges that need to be overcome.

The aim of achieving a preventive risk management approach clearly depends upon having a comprehensive and reliable risk assessment process. A common theme among many of the presentations is that achieving the risk assessment element is challenging, especially for smaller systems. This aspect highlights the need for regulators and professional associations to provide operational support for smaller water providers to implement WSPs. Equally important, some accounts have made the case that risk assessments need to be validated in relation to the reality that potential for system failures that can cause illness in consumers are unacceptable, regardless of what a WSPs risk assessment process may suggest. WSPs must be comprehensive, including extreme events and climate change as part of an all-hazards framework. Likewise, ensuring safe drinking water needs to be implemented within a continuous improvement cycle, including internal and external auditing, to ensure that WSPs stay current and relevant. Evident national and international collaboration on improving WSPs is clearly valuable and should be continued.

Will Carroll (Scottish Water) participated with the Guest Editors in the initial stages of manuscript solicitation and selection.