Wessex Water's sewage treatment works received 368,255.05 Ml of wastewater in 2024-25, about 1,009 Ml a day. That is roughly three times the 334.58 Ml/d of drinking water it put into supply in the same year.
Two populations, one company
The sewerage service reached 2,923,931 residents in 2024-25, against 1,406,053 for the water service. Wastewater connections numbered 1,302,551, about twice the 644,208 on the water side.
A network without a single length
The company's May 2023 drainage plan puts its sewers at about 35,000 km. The Environment Agency uses a baseline of 34,944 km from the financial year ending 2018. The 2024-25 performance tables list foul sewers at 9,278 km, surface water sewers at 4,510 km, combined sewers at 3,137 km and "legacy" public sewers at 18,195 km, categories that overlap. The same plan counts 1,300 storm overflows.
Where the pressure shows
The Environment Agency rated Wessex Water 2 stars in 2024 and 2025, down from 4 stars in 2023. Pollution incidents ran at 46.93 per 10,000 km of sewer in 2025, against a target of 25.02. Spills per monitored overflow fell to 21.08 in 2025 from 33.64, inside a 21.89 target, and sewer collapses were 4.79 per 1,000 km in 2025-26, inside a 6.15 target.
Money for the next five years
The Competition and Markets Authority set Wessex Water's 2025-30 allowed revenue at £3,734 million in 2022-23 prices on 10 March 2026, against £3,875 million requested.
How the water and wastewater systems compare on service results, who regulates each part, and where the outlook points for drought, debt and regulatory reform are set out in the full report. The full report, Water Systems Overview: Wessex Water, is available for USD 499. For a free overview, read the Wessex Water Utility Snapshot.