The Drinking Water Inspectorate published its annual drinking water quality report for 2024 in July 2025, covering England and Wales. The headline compliance figure of 99.97% — meaning 99.97% of the 3.9 million water quality samples tested in 2024 met legal standards — continues a long-running trend of high overall compliance.

However, the report contains a number of important caveats and areas of concern that are worth understanding in context.

What 99.97% compliance means

The 0.03% of samples that failed represents approximately 1,170 individual test failures across England and Wales. Many of these failures involve short-term exceedances that are quickly rectified, and some relate to distribution network issues rather than treatment failures. The compliance metric, while genuinely impressive for a system supplying 56 million people, does not mean that every supply zone is equally clean.

PFAS: the growing concern

The 2024 report dedicates significant space to PFAS (per- and polyfluoroalkyl substances). The DWI notes that PFAS testing has expanded substantially, with water companies now required to test for a broader panel of compounds. The report confirms that 14 water companies in England and Wales are operating under active improvement programmes for PFAS.

Crucially, the DWI reiterates that PFAS detections do not necessarily represent a legal compliance failure — because the UK has no statutory limit for PFAS in drinking water. This is the regulatory gap that the government's February 2026 PFAS strategy is intended to address.

Lead pipes: the legacy infrastructure problem

The 2024 report highlights that approximately 2.5 million homes in England and Wales still have lead supply pipes — a legacy of Victorian-era infrastructure. Lead pipes represent the primary cause of elevated lead levels in drinking water. While water companies add orthophosphate to reduce lead dissolution from pipes, some zones still show elevated lead levels in samples taken at customers' taps.

MyTapWater data tracks zone-level lead mean and maximum values. Areas with older housing stock in Thames Water, United Utilities, and Severn Trent supply zones tend to show higher lead readings.

How to use this data

  • Enter your postcode above to see your specific supply zone's lead, nitrate, THM, and hardness data from the latest annual compliance report
  • The MyTapWater score for your zone reflects the relative performance across all measured parameters
  • If you have concerns about lead specifically, a NSF/ANSI 53-certified filter is effective at reducing lead at the tap

Source: DWI, Drinking Water 2024, published July 2025; DWI public register of improvement programmes.