Thousands of people have signed a petition against controversial plans to replace water from the River Thames in Richmond with treated wastewater. Backers of the petition slammed the proposals from Thames Water and called for the company to fix leaks.

Millions of litres of water a day would be taken from the Thames between Teddington Weir and Hampton Court and transferred via an underground tunnel to the Lee Valley reservoirs under the proposals. Treated wastewater would be moved from Mogden sewage treatment works to replace the water taken from the river.

Thames Water said the scheme would not impact water quality in the river negatively, and that it aims to cut leaks by 50per cent by 2050 but needs more storage due to growing demand and climate change.

But a petition to stop the new abstraction site being built above Teddington Weir has been signed by more than 7,900 people. The petition raises fears about the impact of the scheme on fish, insects and plants, along with concerns the abstraction site would be an "eyesore" and fines imposed for breaches of regulations would not be enough to protect the river.

Teddington Bluetits, a popular local swimming group, targeted Thames Water with protests in January as the company carried out filming for an advert.

It comes as Thames Water was fined £51 million for missed targets by regulator Ofwat in October 2022. The company was given two out of four stars by the Environment Agency in 2021, who highlighted 12 serious pollution incidents and 271 total incidents.

Supporting the petition, Sharon Smith commented: "We don't trust Thames Water to protect the Thames (with good reason) – the fines hardly dent their profits. Do not destroy existing habitats – spend on infrastructure and plug all those leaks to get water in the right place."

David Chan commented: "There's potential damage in operation of the scheme to the local ecology. Thames Water should explore means of stopping leakages from their pipes rather than risk the environment because it is cheaper."

Anna Harrison added: "Rivers need to be clean and the local community is strong in its voice that we do not want treated effluent to be added to the Thames." Jillian White wrote: "I live near the river and don't want to see treated effluent being pumped into it."

Local residents are keen to make their voices heard.

Thames Water put forward the plans in its draft water management plan 2024, which looks at tackling future water shortages and boosting drinking water supply as the population grows and the risk of drought caused by climate change increases. The company estimates it will need an extra one billion litres of water a day for customers by 2075.

The Teddington scheme would be the first introduced under the proposals, by 2031. A consultation on the draft plan ends on March 21. 

A Thames Water spokesperson said: "It's critical that we secure our water supplies for the future, which is why we have launched our draft water resources management plan 24 which sets out the actions and investment needed for the next 50 years. We're proposing to invest in several new strategic schemes that will provide water to the South East, including the new river abstraction at Teddington supported by water recycling.

"We're still in the very early stages of consultation and design. If the scheme is taken forward, there will be detailed option appraisal and design work, where we will carry out engagement and consultation with the local community. 

"The scheme would not negatively impact the river water quality. The treated wastewater effluent taken from Mogden Sewage Treatment Works, would go through an additional stage of treatment to ensure there is no deterioration to the water quality in the river. Putting the recycled water into the river Thames above the Teddington Weir will compensate the river for the additional abstracted water and protect the environment and wildlife.

"The abstraction point also has several features to minimise the impact on aquatic life, boats, water activities and swimmers. The design would reflect best practice and be similar to intakes already in safe operation on the River Thames and elsewhere, and would comply with all relevant health and safety requirements."

The spokesperson added: "Reducing leakage is a priority for us. Right now, around 24pc of the water we supply is lost through leaks from our own network and customer pipes. We know it's not acceptable to be losing so much precious water and we've got a plan to fix it. We've met our target for the last three years, reducing leaks by more than 10pc (from 2017/18 levels), and we're aiming for a 50pc reduction by 2050. 

"We are repairing over 1000 leaks per week – whether they are visible or hidden below ground across 20,000 miles of pipes across our network – that's one leak every 10 minutes. We're also working with our customers to reduce leakage from their water pipes (which make up a third of our total leakage).

"Whilst fixing leaks is one of the foundations of the plan, even with an ambitious target of reducing leaks by 50pc, we still need more storage in the future to account for growing population demand and climate change." 

The spokesperson said the company recently launched a digital map identifying raw sewage discharges via storm overflows to improve performance and transparency, while shareholders have approved an extra £2 billion into the business so it can improve outcomes for customers, leakage and river health.

The spokesperson added: "This will allow us to deliver our commitment to a 50pc reduction in the total annual duration of discharges across London and the Thames Valley by 2030, and within that an 80pc reduction in sensitive catchments. We have started the £100 million upgrade of our Mogden sewage treatment works and are currently increasing sewage treatment capacity at a number of our other sewage works across the Thames Valley, including Witney, Chesham and Fairford to be completed by 2025. We have a long way to go – and we certainly can't do it on our own – but the ambition is clear."