Developing risk assessment approaches for watch list parameters under the recast Drinking Water Directive

This project conducts a first risk assessment for emerging pollutants in drinking water supply sources in Scotland, to identify high risk supply systems and enable prioritisation of monitoring and additional knowledge generation.

In January 2023, a new drinking water standard for per- and polyfluoroalkyl substances (PFAS) was introduced in Scotland. PFAS are a class of synthetic chemicals with broad application such as in packaging, textiles, and firefighting foam, and concerns have been growing over recent years about the potential contamination of surface and groundwater sources with PFAS. A new watch list of substances and compounds of concern also includes drinking water guidance values for two parameters, 17-beta-estradiol and nonylphenol, due to concerns over their endocrine disrupting properties. 

The project reviews current knowledge to identify risk factors for the presence of PFAS, 17-beta-estradiol, and nonylphenol in surface and groundwater, including direct and indirect sources, and processes involved in transfer to and retention in freshwater systems. The project then evaluates public drinking water abstraction catchments for the presence of the identified risk factors. This provides the basis for a strategic monitoring set-up that can subsequently support further understanding of contaminant pathways to drinking water sources, and of efficiency of different treatment approaches and technologies.