How safe is your drinking water? Contamination notices surge 285% over five years

Drinking water contamination alerts in Britain have surged by almost 300% in just five years, new data has revealed, with tap water repeatedly polluted by dangerous chemicals.

Between 2020 and October 2025, 379 drinking water notices were issued across the UK, figures obtained from the Drinking Water Inspectorate show.

The number of notices has climbed from 34 in 2020 to a peak of 131 in 2024, an increase of 285%. Up to October 2025, 93 notices were issued – more than were recorded in 2022 and 2023 combined.

Notices are issued when water quality is compromised or at risk and can require boil notices or supply restrictions. They cover a range of contaminants, including nitrates, PFAS “forever chemicals”, microbial pollution such as E. coli and coliform bacteria. They also include cryptosporidium, a parasite that can cause diarrhoea, vomiting and stomach cramps.

South East Water issued the highest number of notices over the five-year period, with 51 alerts affecting parts of Kent, Surrey and West Sussex. 

The number has grown since then – FOI doesn’t include the most recent South East Water outage and boil notice that impacted tens of thousands of households in Kent and Sussex last November.

Read more:

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Anglian Water ranked second, issuing 49 notices between 2020 and November 2025 across eastern England. Many of the alerts involved detections of PFAS, a group of man-made chemicals linked to agriculture.

Professor Nick Voulvoulis, professor of environmental technology at Imperial College London, said contaminants such as PFAS highlight long-standing pressures on the UK’s water environment. 

“Many of the contaminants involved, from nitrates to PFAS, reflect long-standing pressures on our water environment that current treatment systems were never designed to handle. PFAS, the so-called ‘forever chemicals’, persist in soil and water for decades and build up in the human body, with links to cancers, thyroid disease, and weakened immune response.”

South West and Bournemouth Water issued 45 notices, ranking third. The region has faced repeated microbial alerts, including E. coli and coliform bacteria. 

In May 2023, cryptosporidium entered a reservoir after a damaged air valve, leaving around 17,000 households without water for eight weeks and causing illness in some residents.

All three water companies insisted supplies remained safe while improvements were carried out.

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