Risk assessment and risk management of faecal contamination in drinking water distributed withouta disinfectant residual

In the Netherlands, drinking water is distributed with a low or zero disinfectant residual, resulting in a high appreciation of taste and odour. Even more than in countries striving to maintain a disinfectant residual, water companies in the Netherlands should focus on preventing contamination by guaranteeing reliability of infrastructure and hygiene during operations. The Water Safety Plan approach is being tested in several pilot projects, prioritising needs for further optimisation. Incidence of E. coli (formerly monitored as thermotolerant coliforms) is low. Only 1 in every 1,000 first tap water samples contains these faecal indicators and only 1 in every 25 repeat samples. Repeated detection of faecal indicators occurs only c. five times a year, and outbreaks are rare. Systematic risk assessment, including scientifically based quantitative evaluations, is deemed necessary for effective and cost-effective risk management.