Question to the Department for Environment, Food and Rural Affairs:

To ask the Secretary of State for Environment, Food and Rural Affairs, what recent assessment he has made of trends in the level of per- and polyfluoroalkyl substance contamination in drinking water in England.

Defra works with other departments, regulators and devolved administrations to assess PFAS levels, their sources and potential risks, informing future policy and regulation.

The Drinking Water Inspectorate (DWI) has provided guidance on PFAS since 2007, most recently updated in August 2024 and consolidated in March 2025. The guidance uses a tiered system with graduated responses based on concentrations detected in raw water.

In 2021 a guideline value of 0.1 micrograms per litre (µg/L) was adopted. Since August 2024, water companies must monitor for 48 PFAS in supplies, agreed with the UK Health Security Agency as safe levels with an appropriate margin. Any exceedance must be reported to the DWI, with actions taken to reduce levels. No exceedances have been found in UK supplies.

The DWI continues to review advice from World Health Organisation and the UK’s Committee on Toxicity, acting on emerging science to safeguard public health.