England’s water companies face poor ratings as serious pollution rises

Eight of England’s nine major water and sewerage companies were rated poor or requiring improvement in the Environment Agency’s environmental assessment for 2024. The findings, published on 23 October 2025, showed serious pollution incidents increased by 60% from the previous year.

Thames Water received the lowest rating of one star, while seven companies received two stars. Severn Trent Water was the only company awarded the maximum four stars, maintaining that rating for a sixth consecutive year.

The industry collectively earned 19 stars out of a possible 36, compared with 25 in 2023. Although that was the lowest total since the assessment began in 2011, the agency cautioned that standards have progressively tightened, making straightforward historical comparisons misleading.

The regulator’s separate pollution report recorded 75 serious incidents in 2024, up from 47 in 2023. Thames Water accounted for 33, Southern Water for 15 and Yorkshire Water for 13, together representing 81% of the total. Northumbrian Water and Wessex Water recorded none.

Across all three recorded pollution categories, incidents involving sewerage and water supply infrastructure increased by 29% to 2,801. It was the third consecutive annual increase. The agency said the sector remained far from its expectations for reducing pollution, with total incidents 47% above their 2016 level.

The Environment Agency identified wet and stormy weather, underinvestment and poor infrastructure maintenance among the factors behind the disappointing results. Increased monitoring and inspections also contributed to a clearer picture of performance. It called for changes in company culture and leadership alongside improvements to physical infrastructure.

Reporting performance presented a mixed picture, according to the pollution report. Companies themselves reported 85% of all recorded incidents, the strongest overall result to date, but their self-reporting rate for serious incidents fell from 74% to 63%. Only four of the 11 incidents in the most serious category were self-reported.

Timely reporting matters because it gives operators and regulators an opportunity to limit environmental damage. The agency said delays can allow pollution impacts to escalate and opportunities for mitigation to be lost. It expects particularly strong reporting from treatment works and pumping stations, which normally have staff or alarms.

Delivery of environmental improvements was another concern. While 97% of schemes assessed under the Water Industry National Environment Programme met requirements within planned deadlines over the five years ending March 2025, six companies missed at least some obligations. Unfinished schemes were transferred into the next investment programme for continued oversight.

The agency said it was strengthening regulation through additional staff, digital systems and inspections. At publication, it reported more than 4,600 water company inspections in 2024–25 and a target of 10,000 for 2025–26. Its stated priority was to turn stronger scrutiny and company commitments into measurable improvements in environmental performance.