Battleground seats held by the Conservatives have the highest number of sewage spills of any marginal constituencies, The Times has found.

George Willoughby, Adam Vaughan www.thetimes.co.uk 

The figures show how exposed Tory MPs are to attacks over the party’s record on water pollution. Seats won in the 2019 general election by a margin of less than 10 per cent will be crucial when people next vote.

The Times can reveal that of the 79,467 sewage spills in marginal constituencies in 2022, over 39,000 were in Conservative seats, more than those held by any other party. Labour marginal seats were second at little more than 26,000.

The Liberal Democrats have made sewage one of their top campaign issues, with Sir Ed Davey, the party leader, saying Tory voters were “very, very angry” over spills.

Since being appointed last September, Steve Reed, the shadow environment secretary, has also concentrated on water quality, saying the “sewage scandal” was a result of “Conservative failure”.

Polling of 6,000 adults by Survation found that 56 per cent of people would consider raw sewage discharges when they voted in the next general election. The number for those who voted Tory in 2019 is 51 per cent, whereas for Labour voters it is 66 per cent.

The high number of spills in Tory-held marginal seats appears to be a ­result of the party’s gains in “red wall” areas in 2019. About 25,000 spills in 2022 were in marginal constituencies the party gained from Labour. About 14,000 sewage discharges were in marginal seats the Tories held in 2019.

The Welsh constituency of Carmarthen East & Dinefwr, held by Jonathan Edwards, the former Plaid Cymru MP who is now an independent, had the most sewage spills of all marginal seats, with 7,103 dumps. Edwards holds a 4 per cent majority.

The Arfon constituency, held by Plaid Cymru, had the second most spills for a marginal seat, followed by three Tory consituencies: Ynys Môn, North West Durham and Aberconwy.

The drier weather last year is believed to have led to a slight fall in the number of sewage spills.

Discharges happen mostly during heavy rain when sewer capacity is overwhelmed. Sewage releases are often a result of geography and water company infrastructure. Having a high number of spills in their constituency can leave MPs ­vulnerable to criticism, however.

The Lib Dems attribute their victory in the 2021 Chesham & Amersham by-election to their concentration on polluted local chalk streams. One of the marginal seats in the party’s sights is Cheltenham, held by Alex Chalk, the justice secretary, with a majority of 981.

Tim Farron, the Lib Dem environment spokesman, said the Tories’ failure to tackle the sewage crisis would cost them seats at the next election. “Lifelong Conservative voters are planning to vote Liberal Democrat for the first time because of this,” he added.

Labour is yet fully to set out its stall on how it would tackle water pollution. The Tories recently pinched one of the party’s headline ideas: ending self-monitoring of water companies.

Rebecca Pow, an environment minister and MP for Taunton Deane, said: “We have a plan and it’s already in place. The water companies have to be taken into account.”

Reed said: “This Conservative government has meekly sat back … while toxic sewage pollutes our waterways.”