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

To ask the Secretary of State for Environment, Food and Rural Affairs, what the most recent results were of tests for PFAS levels in Thames Water.

In England and Wales, the Drinking Water Inspectorate (DWI) has provided guidance to water companies since 2009 which ensured that two key PFAS substances were considered in their risk assessments. The guidance was updated in January 2021 to reflect current knowledge and include consideration of other PFAS:

www.dwi.gov.uk/private-water-supplies/pws-installations/guidance-on-the-water-supply-water-quality-regulations-2016-specific-to-pfos-perfluorooctane-sulphonate-and-pfoa-perfluorooctanoic-acid-concentrations-in-drinking-water/

In October 2021, the DWI wrote to water companies informing them of additional requirements for sampling, testing and monitoring for PFAS in raw water sources from which abstractions are used for drinking water. The Inspectorate is in the process of assessing the information provided by companies, so we are unable to provide specific results for Thames Water. Where appropriate, DWI will share any relevant learning on PFAS through the publicly available Chief Inspector's Report.