Drinking water and public health: Prevention, detection and response to waterborne outbreaks in Norway

Access to safe drinking water is highly important for public health. In Norway, most people have access to reliable sources of drinking water and high-standard water supply and sanitation services. Despite precautionary actions, however, every year events implying a health risk occur in Norway, in addition to large waterborne outbreaks such as the Campylobacter-outbreak in Askøy in 2019. This outbreak is a strong reminder of the vulnerability of water supply systems. In this thesis, a multidisciplinary approach is used to meet the overall objective of preventing waterborne outbreaks by examining the risks in the water supply system, the early detection of waterborne outbreaks and public compliance with boil water advisories. A specific concern can arguably be linked to an aging and vulnerable distribution system prone for contamination. In addition, changing climate parameters serve as stressors and induce critical events. In case of a contamination event evolving into a waterborne outbreak, there is no clear evidence that syndromic surveillance may serve as early detection, at least not for smaller and local waterborne outbreaks with an acute onset of illness. Public compliance with boil water advisories is affected by awareness and the perception of the severity of the situation; compliance is lower if the risk of illness is perceived as low. The findings demonstrate that preventive long-term precautionary actions and conducting risk-based surveillance of drinking water supplies are essential to limit societal consequences. Effective communication of health advice is also imperative to ensure high compliance. The findings adds to the knowledge of preventing, detecting and response to waterborne outbreaks in Norway, and contribute to putting emerging risks in the drinking water supply on the agenda