Water suppliers worldwide are challenged by climate variations, but so far only the qualitative change in boundary conditions has become clear but not yet the degree and impact on the water supply systems. Short-term quality changes in surface waters can, e.g. be caused by extreme rainfalls after dry periods. Longer heat periods without rain can induce middle-term quality changes in surface waters due to lacking dilution. Furthermore, unsustainable management of groundwater can lead to long-term quality changes and to water shortages, especially in times with higher water demand. Depending on the individual situation, the expected effects on the supply system differ widely, so a general adaptation strategy will not suit the individual problems. The purpose of our work is to enable water supply companies to systematically identify potential risks resulting from climate change and other external factors in a water safety plan approach, and to adapt the supply system in a most effective way by taking advantage of ongoing modernization measures and ‘no-regret’-measures. A suitable adaptation strategy should address climate change conditions as well as other external factors like changing water demand and also to take into account possible effects on every part of the supply system.

Against the background of price controls for drinking water supply utilities in Germany, the comparability of utilities with regard to their specific structural conditions comes into focus. Relevant structural conditions were identified for the two main technical processes, namely water production (WP) and treatment, storage and distribution (TSD). A defined clustering process for comparable utilities has been developed. At the end of the process, groups of comparable utilities are obtained including information to what extent and in which structural condition these utilities are similar. These sets of relevant structural conditions and the clustering process were verified in a data assessment study with 45 German utilities. Applying the clustering process to the sample, WP and TSD peer groups of a certain utility are obtained, where structural similarities are above a certain threshold value. Performance and cost indicators of comparable utilities have been evaluated, providing interesting data on general performance levels and spread among individual utilities. The survey underlines the high standard of German water supply in terms of reliability, quality, customer service, sustainability and economic efficiency.

According to the recommendations of the World Health Organization (WHO) for Water Safety Plans (WSP), a Technical Risk Management was developed, which considers standard demands in drinking water treatment in Germany. It was already implemented at several drinking water treatment plants of different size and treatment processes in Germany. Hazards affecting water quality, continuity, and the reliability of supply from catchment to treatment and distribution could be identified by a systematic approach, and suitable control measures were defined. Experiences are presented by detailed examples covering methods, practical consequences, and further outcomes. The method and the benefits for the water suppliers are discussed and an outlook on the future role of WSPs in German water supply is given.

For many water supply companies, the sustainable exploitation of water resources has always been an integral part of their business, voluntarily accepting tasks and responsibility which benefit society and the environment in general, e.g. in resource protection, environmental monitoring, and encouragement of sustainable farming practices. However, these voluntary activities are often not sufficiently recognised internally and externally due to a missing sustainability framework and a less developed communication strategy. Therefore, a comprehensive framework for the measurement and reporting of corporate responsibility (CR) in water supply was developed, comprising the environmental and sustainability issues of resource protection and water supply, social responsibility and long-term economical development. This framework was successfully applied in a Balanced Scorecard (BSC) approach and served as basis for a CR report of a German regional water and wastewater company. The CR Performance Indicator system was imbedded in the IWA framework of Performance Indicators (PI), and as such is universally applicable in water and wastewater systems.

A Technical Risk Management based on the Water Safety Plan (WSP) concept was implemented at four German water supply systems according to the recommendations of the World Health Organization (WHO). Hazards affecting water quality, continuity and the reliability of supply from catchment to treatment and distribution could be identified by the systematic approach and suitable measures were defined. The results of four successful implementations of the extended WSP-concept are presented in a detailed case study, covering methods, practical consequences and further outcomes. The method and the benefits for the water suppliers are discussed and an outlook on the future role of WSPs in German water supply is given. For the acceptance of the WSP approach among German suppliers it was essential that the original WHO scope on health issues was widened to supply targets (quality, quantity, pressure, continuity of supply). Positive results from successful pilot implementations increased the acceptance for WSP and proofed the benefit for the operators. Currently, the WSP concept is being prepared to fit into the German technical guideline, thus anticipating a revised European Drinking Water Directive likely to include Water Safety Plans.