A WATER company spilled raw sewage into sensitive streams in Test Valley on nearly 500 occasions within just one year, new data has revealed.

Southern Water dumped untreated sewage into rivers Test and Blackwater for more than 7,983 hours.

Data from the government, and compiled by the Rivers Trust, relating to 12 sewer storm overflows in 2020 revealed the sheer scale of the spills.

The highest number of occurrences were at Stockbridge Water Treatment Works (WTW) where there were 124 spills, resulting in more than 2,200 hours of spillage, followed by West Wellow WTW where there were 112 spills over more than 2,274 hours.

Water companies are allowed to release untreated waste when the system becomes overwhelmed. It prevents sewage from backing up into houses and through manhole covers.

The issue hit the headlines last year when the government ordered its MPs to vote against an amendment that would have banned water companies from doing this, but Romsey and Southampton North MP, Caroline Nokes rebelled against the government.

Shortly after the amendment was voted down, the government made a U-turn, of sorts, putting forward an amendment of their own which would “secure a progressive reduction in the adverse impacts of discharges from storm overflows”.

Ms Nokes said: “I am very conscious that I am not just the MP for a very long stretch of the River Test but also for a short stretch of the River Itchen, which runs through part of Swaythling. They are indisputably two of the finest chalk streams in the world, but also under severe stress, and have been for decades.

“Back in 2020 I was one of the original parliamentary backers of Philip Dunne’s Private Members Bill, the Sewage (Inland Water Ways) Bill which ran out of Parliamentary time but aimed to tackle the discharge of raw sewage into our rivers so when the amendment came forward to the Environment Bill, which effectively secured the measures, Philip had been seeking, I clearly wanted to support it. I found myself in the lobby with a number of other MPs who have Southern Water operating in their constituencies.

“It is important to reflect, Southern Water has a poor track record, which culminated in a record fine of £90m last year, for their illegal discharges into rivers and coastal waters.

“That amendment was defeated, but when the Bill next came back to the Commons the Government had introduced its own amendment, in lieu of the Lords Amendments, which places a duty on water companies to secure a progressive reduction in the adverse impact of discharges from storm overflows. This was the essence of the clause in Philip’s PMB and which the Duke of Wellington had taken forward in the Lords.

“It is always worth reflecting that none of us want sewage discharged into our rivers, but equally none of us want it in our houses either. I have been in some of the villages in this constituency that have had to have “overpumping” deployed in order to prevent raw sewage from bubbling up through lavatories and plug holes and into people’s bathrooms and kitchens. I have stood in people’s kitchens ankle deep in sewage and know the devastation that causes to homes and families. So that is why I support a progressive reduction, which companies like Southern Water will now have to implement.”

A Southern Water spokesperson said: “Storm overflows are heavily regulated releases of wastewater which predominately occur during periods of heavy rainfall and are an integral part of our Victorian-era sewage system, protect people’s homes and businesses and other properties from the misery of flooding. Despite the fact these releases are typically more than 95 per cent rainwater, we know we must reduce the frequency and impact of these spills.

“To do this we have recently launched a CSO taskforce which alongside £2 billion of investment into our wastewater network and industry-leading Pollution Incident Reduction Plan, will help us deliver an 80 per cent reduction in pollution incidents and storm overflows by 2025 and 2030 respectively.”

“The twin pressures of climate change and a growing population mean that Hampshire needs new water sources to keep local taps and rivers flowing today and in the future.

“By tackling leakages, improving water efficiency and investing in new pipelines and reservoirs, our Water for Life Hampshire programme will help reduce the amount of water we source from the Test and the Itchen, resulting in a higher quality and more resilient water supply for our customers and the environment, whatever the weather.”

The data:

Stockbridge Water Treatment Works: 124 spills, 2,200.99 hours

• Kings Somborne Water Treatment Works: 118 spills, 2,043.48 hours

• West Wellow Water Treatment Works: 112 spills, 2,274.62 hours

• Wellow Mill Blackhill wastewater pumping station: 53 spills, 664.89 hours

• Romsey Water Treatment Works: 48 spills, 593.04 hours

• White Hart Lane, Stockbridge wastewater pumping station: 13 spills, 58.23 hours

• Whiteparish Water Treatment Works: 9 spills, 56.85 hours

• Ringwood Park, North Baddesley wastewater pumping station: 8 spills, 34.95 hours

• Green Lane, Chilworth, wastewater pumping station: 7 spills, 20.12 hours

• Saddlers Mill, Romsey, wastewater pumping station: 3 spills, 33.62 hours

• Houghton Road, Stockbridge: 1 spill, 0.97 hours

• Anton Lane, Andover (River Anton): 1 spill, 1.35 hours