Shock analysis reveals longest sewage “spill” - including one which lasted a whole year

EMBARGO: 22.30 Thursday 10th April 2025

• Liberal Democrat analysis can reveal the top 10 longest sewage spills last year with the longest sewage dump lasting 366 days owing to the leap year
• Party is calling for a ban on bonuses for water company bosses and the scrapping of toothless regulator Ofwat

Liberal Democrat analysis of Environment Agency data reveals the shocking extent of sewage spills polluting British seas and rivers. This is despite water company bosses earning a collective total of over £20 million in the financial year 2023/24.

The worst spill was from South West Water, which reported spilling sewage from one outlet into Salcombe Regis Stream for 366 days - thanks to the leap year of 2024. That is a huge increase on the previous year, when sewage was pumped from that same site for the equivalent of 201 days.

South West Water was the worst offender overall, placing first, fourth and seventh in the top ten list with spills lasting for 366 days, 258 days and 224 days, respectively.

Southern Water recorded the second longest spill, lasting 285 days, into the River Lavant. This river flows directly into Chichester Harbour - a protected site and area of special scientific interest and conservation. This comes after a study this week revealed that chemical pollution in Chichester Harbour increased more than 100-fold after sewage discharges.

Wessex Water places third with a spill continuing for over 269 days into River Bourne in Wiltshire. Anglian Water’s longest sewage spill comes in at number five, with a spill lasting 229 days.

Southern Water appears in the top ten for a second time, in sixth place, with a spill pumping disgusting sewage into a tributary of the River Test for over 228 days.

Northumbrian Water revealed that they had a spill which lasted 224 days - the eighth longest spill of 2024. Thames Water is ninth with a spill that lasted over 223 days, into Mill Brook. At ten is Severn Trent, with a 217-day spill into Quinny Brook, which flows through the Shropshire Hills National Landscape.

This comes after Liberal Democrat analysis reveals that company executives received over £20m in total last year - including basic pay, pension contributions and bonuses.

The Liberal Democrats have spearheaded the campaign to clean up British rivers and seas, calling for Ofwat to be scrapped in favour of a new regulator to clamp down on polluting water companies. 

Commenting, Leader of Liberal Democrats Ed Davey said:

“It is horrifying to know that sewage has been pumped into British rivers, and disgracefully in South West Water’s case, disgusting sewage has polluted water every single day last year - all 366 days of it.

“Even worse, while the sewage scandal drags on and on, company executives are pocketing eye-watering bonuses and customers face spiralling bills.

“Enough is enough. Conservative Ministers ignored the sewage scandal for too long, and the Labour government seems to be following suit. We urgently need a tough new regulator with real teeth, and an immediate ban on bonuses for the executives damaging our environment.”

ENDS

Notes to Editor:

The data analysed by the Liberal Democrats is taken from DEFRA’s Annual Reports of  Storm Overflows

https://environment.data.gov.uk/dataset/21e15f12-0df8-4bfc-b763-45226c16a8ac

The top ten sewage spills in 2024 are available here.

The figures on water company remuneration can be found in a previous press release.

The BBC report on Chichester Harbour’s chemical pollution can be found here.