Implementation and evaluation of the water safety plan approach for buildings

The World Health Organization (WHO) promotes water safety plans (WSPs) – a risk-based management approach – for premise plumbing systems in buildings to prevent deterioration of drinking-water quality. Experience with the implementation of WSPs in buildings were gathered within a pilot project in Germany. The project included an evaluation of the feasibility and advantages of WSPs by all stakeholders who share responsibility in drinking-water safety. While the feasibility of the concept was demonstrated for all buildings, bene ﬁ ts reported by building operators varied. The more technical standards were complied with before implementing WSP, the less pronounced were the resulting improvements. In most cases, WSPs yielded an increased system knowledge and awareness for drinking-water quality issues. WSPs also led to improved operation of the premise plumbing system and provided bene ﬁ ts for surveillance authorities. A survey among the European Network of Drinking-Water Regulators on the existing legal framework regarding drinking-water safety in buildings exhibited that countries are aware of the need to manage risks in buildings ’ installations, but experience with WSP is rare. Based on the successful implementation and the positive effects of WSPs on drinking-water quality, we recommend the establishment of legal frameworks that require WSPs for priority buildings whilst accounting for differing conditions in buildings and countries.


INTRODUCTION
Improving the WASH conditions in schools and health care facilities is also in the focus of the United Nations Economic Commission for Europe and WHO Regional Office for Europe Protocol on Water and Health (WHO b). In the WHO European Region, the Ostrava Declaration on Environment and Health also promotes universal, equitable and sustainable access to safe WASH for all and in all settings, including schools and health care facilities (WHO a). An assessment of the situation in schools in the WHO European Region revealed prevailing deficiencies in terms of availability, accessibility and acceptability of WASH facilities (Grossi et al. ). In 2018, the European Commission suggested introducing a risk assessment for building premise plumbing systems in their proposal for a revised directive on the quality of water intended for human consumption (European Commission ).

Microbiological problems in premise plumbing systems
The proliferation of pathogens, such as Legionella and  (Craun et al. ). This fact reveals an urgent need to pay more attention to premise plumbing systems and point-of-use issues (Craun et al. ). Also, in Europe, a continuous increase of cases of Legionnaires' disease has been observed. Although not every outbreak is associated with drinking-water, premise plumbing systems (warm and cold water) are one of the main sources of infection with Legionnaires' disease (Robert Koch Institut ). In 2011, 4,921 cases were reported for 30 European countries, which equals an average rate of 1.0 cases per 100,000 inhabitants. In 2015, the number increased to 7,034 reported cases, which equals an average rate of 1.4 cases per 100,000 inhabitants (European Centre for Disease Preventionand Control ). The highest rate of 5.1 cases per 100,000 inhabitants was detected in Slovenia. The highest number of detected cases (1,389) were reported in France with an average rate of 2.1 and in Italy with 1,556 cases and an average rate of 2.6 cases per 100,000 inhabitants.
In France, the number of cases has remained stable in recent years (Campèse et al. ) and an investigation of private buildings showed the presence of Legionella in 26% of the analyzed hot water systems, which corresponds with further data from Italy (Totaro et al. ).

Other problems in premise plumbing systems
Drinking-water systems in buildings consist of complex piping installations and include various components: it begins with the point of entry into the building or the premise, water piping, storage systems, and devices for supplying hot water. Deficiencies in design, construction, operation and use of water installation systems can cause hazards that may also impact the safety of drinking-water. These deficiencies include cross connections with non-potable water systems (e.g. greywater, fire mains) or drainage systems and the use of inappropriate materials that leach hazardous chemicals (e.g. lead). Review data regarding 26 incidents of outbreaks associated with distribution systems demonstrate that cross-connections are one of the main deficiencies (Moreira & Bondelind ). Exceedance of the limit value of lead in the EU is mainly connected to the premise plumbing system in buildings (European Commission ).

Water safety plan approach
The WHO Guidelines for drinking-water quality recommend the water safety plan (WSP) approach, which is based on risk assessment and risk management principles, to consistently ensure the quality of drinking-water from the catchment to the point of use (WHO b). WSPs can be applied to all water supplies and it has already been successfully applied in buildings (e.g. Dyck et al. ; Kumpel et al. ). The key steps of a WSP are ( Figure 1 A WSP in buildings always starts with the formation of a team whose members conduct the steps presented in

Legal situation in Germany
In Germany, the drinking-water ordinance (TrinkwV ) prescribes minimum requirements to ensure drinking-water quality. According to the ordinance, the building owner is responsible for the management of the drinking-water installation in buildings and for ensuring compliance with  were responsible for operation of the system. They attended technical advanced training and were supported by external companies who conducted maintenance of the system. The quality of drinking-water was tested annually, which is more frequent than legally required.
Building B included a canteen kitchen, a swimming pool and public sport facilities with showers that were situated on an area of about 43,000 m 2 . The kitchen and sport facilities were supplied by two separated warm water circulations. Increased concentrations of Legionella were detected in the past. After this incident the awareness of the building management for the risk of Legionella growth was raised, and due to that staff gained knowledge in the field of drinking-water hygiene and premise plumbing systems.
The hospital (building C) provided space for 207 patients, who were cared by 250 employees, in 25 separate buildings, resulting in a very complex premise plumbing system: the warm water distribution system had a length of 2 km and the cold water distribution system was 1 km in length. As part of reconstruction works, the warm water supply was mostly decentralized to reach a temperature of 60 C in the whole warm water system. The three technical employees, who were responsible for the premise plumbing system, attended training that focused on the topic of drinking-water premise plumbing systems and therefore were aware of risks related to drinking-water.
Around 8,000 employees were working in the company building complex (building D) that consisted of ten individual factory halls with a total area of 260,000 m 2 . Apart from a complex drinking-water premise plumbing system, there were networks for fire extinguishing, cooling and water used for non-drinking purposes, as well as networks for different liquids (such as oil). In response to a contamination event with Legionella, the company established a working group that was responsible for activities concerning drinking-water hygiene and had already implemented control measures to prevent Legionella contamination.

Application of WSPs
At the beginning of the implementation, project members • Assessment of the WSP approach and its applicability for building management; • Assessment of individual WSP steps, their feasibility and usefulness; • Resources needed for WSP implementation; • Assessment of further support needs for a successful implementation; • Identification of benefits of the WSP approach compared to previous practices; • Evaluation of the potential of WSP outcomes to support the surveillance of buildings by health authorities.

Survey on the legal situation in Europe
Besides this pilot project, we sent a questionnaire to mem-

RESULTS AND DISCUSSION
The presented results of the pilot project focus on the feedback from all project members and the way they assessed the feasibility of the WSP approach, the availability of resources and the expertise needed. Furthermore, generally perceived benefits were determined as well as the impacts on the premise plumbing systems and the protection of drinking-water quality.

Impacts and benefits of WSP in buildings
Based on the feedback of the project members, Table 2 summarizes the impact of the individual steps of WSP implementation as the project members assessed them. The difference between the assessment of the WSP approach by the operators in building A compared to buildings B, C and D showed that the acceptance by the operators and the necessity to implement a WSP strongly depends on the prevailing conditions of the premise plumbing system.
Although the WSP led to improvements of the premise plumbing system and its operation in all four buildings, the impact of improvements in building A was less significant due to the better initial conditions. Similarly, the efforts needed to implement the WSP also depended on the prevailing state of the system and on expertise of the technical staff. Due to the work within the team, all participants were able to broaden their knowledge and therefore they were well prepared for possible future difficulties. The cooperation between the different stakeholders was a main advantage to ensure sustainable operation of the system and monitoring. Table 3 shows a more detailed description of the benefits of a WSP and how it improved the premise plumbing system and its operation, as reported by the project members, in accordance with the categorization provided by WHO (b).

The assessment of the implementation in buildings B
and D exhibited the highest improvements: systematic examination led to an increased understanding of the whole premise plumbing system and therefore to an enhanced knowledge of existing hazards, hazardous events and risks by all stakeholders. An exchange of information and

WSP team and joint site inspection
Hazard analysis and risk assessment þ to hazard occurrence. Nevertheless, the teams emphasized the benefit of discussing and systematically assessing prevailing risks, and the outcomes of these joint team evaluations were commonly accepted by building management. Team members noted, however, that the risk assessment required sufficient technical, water quality and health expertise of the team members in order to reach sound conclusions, and therefore external support may be required where such expertise is lacking.

Responsibility of health authorities and WSPs' advantages for their surveillance activities
In their assessment of the WSP approach, the local health authorities emphasized their limitation in human and time resources. They highlighted that a general involvement of the local health authorities into the entire process of WSP implementation is not feasible; their support had to be restricted to high priority buildings (e.g. with known problems concerning drinking-water or hosting vulnerable persons) and in response to incident situations. Furthermore their support should focus on key steps of the implementation such as hazard analysis, risk assessment and an external evaluation of the adequacy and effectiveness (audit) of the WSP.
The building management, in turn, asserted that the expertise of the local health authorities was indispensable during the WSP process. In particular, their health expertise and their impartiality of commercial interest was assessed  Local health authorities viewed implementation of the WSP approach beneficial for official surveillance purposes and for maintaining a cooperative relation with the building management. A complete documentation of the premise plumbing systemwhich is often missingand of prioritized risks supported a systematic approach to the monitoring of local conditions. Additionally, through the WSP process, the local health authority's expectations regarding drinking-water quality and the premise plumbing system became more transparent for the building managementtherefore cooperation between them was enhanced and it was easier to comply with these requirements. Simultaneously, collaboration also ensures more confidence in the quality of the WSP.
Since project members considered it as not feasible to involve health authorities in the whole WSP process in every building, the support by external experts as well as • Authorization of water suppliers to carry out regular inspections of fittings and to take action if issues arise; • Use of specific recommendations for water suppliers and plumbers; • Established requirements for maintenance and testing by a mandated authority, and depending on the test results, initiating remedial actions; • Defined sampling frequency and testing parameters for priority buildings; • Defined specific monitoring of lead; • Control of Legionella, including specific recommendations for health care facilities and special legislation for an assessment for Legionella.
The findings indicate that countries are aware of the importance of reducing risks that are caused by deficiencies in the premise plumbing systems and have individual approaches to control them. However, a legally binding requirement for risk management in buildings is not in place in most cases, and if in place they focus merely on priority buildings.

Regulatory considerations
The experiences from the German pilot project clearly show that significant improvements of the premise plumbing system and its operation are possible. A requirement for developing such a document could also be used and adapted in other settings towards a more comprehensive description of the condition of the premise plumbing system and documentation of all information necessary.

CONCLUSIONS
The experiences of the pilot project show that the WSP approach provides great potential to discover deficiencies and to improve the conditions of building's premise plumbing systems and hence protect drinking-water from contamination. A WSP leads to smaller improvements in buildings with new premise plumbing systems that are planned and constructed in accordance with state-of-theart technical standards and are well-managed, operated and maintained. The WSP approach will likely show more significant advantages and improvements for buildings which are complex, older and where diligent water quality management is not in place.
An up-to-date description of the premise plumbing system and the outcomes of the hazard analysis and risk assessment clearly support building operators in identifying existing deficiencies and implementing improvement measures in a structured way. The cooperation in the team increases knowledge and awareness of team members, and the periodic review of the WSP approach supports meeting water quality targets and sustainability of the system operation. The WSP approach also improves understanding Benedict et al. ) and numbers of notified cases of Legionnaires' disease reveal the importance of extending a riskbased management approach to the drinking-water premise plumbing system for ensuring the quality of drinking-water at the point of consumption. Therefore, it is advantageous to establish a legal framework that specifies minimum requirements for the principles that underpin a WSP and defines the responsibilities of all stakeholders. This process needs to consider several factors, including: • existing legal requirements and technical standards; • an analysis of required versus available expertise and resources needed for implementation; • enforcement and reasonableness of such requirements for different types of buildings; • the prevailing conditions of premise plumbing systems; • reported compliance with drinking-water quality standards at the point of consumption; and • known adverse health outcomes related to water quality in buildings.
Expertise regarding the implementation of WSP in buildings tends to be still low in EU member states.
Therefore, time and resources are needed to build capacity and experience and to implement legal requirements for WSP profoundly. Cooperation and exchange of knowledge should be supported at all levels.