PFAS ('forever chemicals')

Drinking water is only one possible route of exposure to PFAS, accounting for a small proportion of the possible overall exposure alongside the use of various chemical products, food and even household dust.

There are PFAS currently being used within a range of industries.

There are some PFAS that have had their use restricted. For example, perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) have been restricted in England and Wales through UK REACH, the regulatory framework for the Registration, Evaluation, Authorisation and Restriction of Chemicals.

Work is being carried out by the European Chemicals Agency (ECHA) to restrict the production and import of all PFAS.

Some PFAS, such as PFOA and PFOS have been associated with adverse effects in animal and human studies at sufficient levels of exposure. This has led to the restricted use of some of these substances in a variety of global markets. For many PFAS compounds there is a lack of toxicological data and research is still ongoing to better understand the health effects associated with low levels of exposure over long periods of time.

Recognising the potential for longer term accumulation of some PFAS in the human body, the independent quality regulator for drinking water the Drinking Water Inspectorate (DWI) has set guidance levels for PFAS that provide a precautionary margin of safety in advance of further international research on PFAS toxicology.

Based on current knowledge, the Drinking Water Inspectorate states that the low levels of PFAS detected in some untreated water abstracted for public drinking water supplies have no acute or immediate impact on human health.

For PFAS compounds in drinking water, and in response to emerging data from the Environment Agency about environmental risks, in 2021 the DWI set guidance requiring companies to monitor for a wide range of PFAS and update their risk assessments accordingly.

We are currently monitoring our sites on a risk-based basis for the PFAS set out in DWI's guidance.

Where PFAS concentrations are above the DWI guidance value, they can be removed from water at varying rates using granular activated carbon (GAC), powdered activated carbon (PAC), ion exchange and reverse osmosis membranes.

Water supplies can also be managed, and concentrations diluted through the blending of water.

Drinking water in the Wessex Water region is clean, reliable and consistently of a high quality with water in the UK being considered some of the best in the world. We use the World Health Organisation risk-based water safety planning approach to identify and mitigate any potential risks to drinking water from source to tap.

The water industry regulatory system and standards are designed with a high level of conservatism and include health-based limits. Our water supplies are managed using risk assessment, sampling and monitoring, and treatment processes to achieve the stringent regulatory standards.

We, along with other water companies, are in the process of assessing and monitoring these chemicals to identify them, measure likely concentrations and assess the need for future mitigations. Water companies are providing this data back to the regulator and DWI will subsequently report on the findings of this process and provide insight into the overall picture of PFAS for Drinking Water in England and Wales.

We are also supporting the DWI in working closely with the UK Health Security Agency, the Environment Agency and government, to adopt the most up-to-date information regarding standards and toxicology. We will also continue to support the work being done by the European Federation of National Associations of Water Services (EurEau) advocating for enforcement and environmental regulation to prevent PFAS at source.

We will continue to monitor our sites on a risk-based approach along with developing our risk assessments as more data becomes available to inform these risk assessments.

We have a drinking water strategy for PFAS with a clear action process in place to ensure we are monitoring our supplies and working to identify potential sources of PFAS within our catchments.