MPs raise concerns over Southern Water's plans to recycle wastewater into future drinking water supply
A growing number of MPs have voiced concerns over Southern Water's plans to use highly treated recycled wastewater to help replenish Havant Thicket Reservoir, with campaigners calling for a wider public debate before the technology becomes part of the UK's drinking water system.
Controversial plans to pump recycled water into the new Havant Thicket Water Reservoir took a key step forward in June – with Southern Water officially asking for permission to go ahead with the scheme.
The £1.3bn project would involve treating and cleaning wastewater at Budds Farm Wastewater Treatment Works in Havant before it being used to top up the new reservoir being built by Portsmouth Water, in partnership with Southern Water.
The proposal forms part of long-term plans to improve water security across Hampshire and West Sussex as climate change, population growth and environmental protections place increasing pressure on existing water resources.
Campaign group Save Our South Coast Alliance (SOSCA) says the project could set a national precedent and argues that alternatives – including building additional reservoirs, capturing more winter rainfall, reducing leakage and improving water transfers—should be fully examined before recycled wastewater is introduced into drinking water supplies.
A SOSCA statement read: “A growing number of MPs have raised concerns over Southern Water’s controversial proposal to use highly treated recycled wastewater to help replenish Havant Thicket Reservoir, arguing that the proposal risks becoming a precedent for the rest of the country without adequate public consultation – especially across West Sussex, or a full examination of alternative solutions.
“Among those voicing concern are Alan Mak, Jess Brown-Fuller and Suella Braverman, who have each raised the issue in Parliament or on their Facebook accounts.
"The initial cost of £340 million Havant Thicket Reservoir, the world’s first spring fed reservoir, currently under construction near Havant Hampshire, is intended to improve water security across Hampshire and West Sussex.
"However, Southern Water have now submitted their Development Consent order application as the first step towards introducing recycled wastewater directly into the reservoir to supplement the regions public water supply with very little public awareness, or consultation with customers.
"Opponents are arguing that the alternatives – including more reservoirs, capturing more winter rainfall and expanding local water storage, moving river abstractions to the tidal limit to reduce impact, reducing leakage, and improving water transfer infrastructure – should be fully evaluated before water companies invest billions of pounds of customers money in what critics describe as one of the most energy-intensive, environmentally damaging and expensive methods of increasing water supplies.”
The group also questions whether comparisons with countries including Australia and parts of the United States are appropriate, arguing that the UK's water challenges differ because much seasonal rainfall is not currently stored.
Southern Water says the project has been developed in response to increasing pressure on water resources and forms part of a wider programme of investment designed to improve resilience while reducing abstraction from environmentally sensitive chalk streams, including the Rivers Test and Itchen.
Ben Ring, managing director for capital projects at Southern Water, said the company recognised that people had questions about the project but rejected suggestions that it had progressed without public consultation.
"We have held multiple rounds of public consultation as the Project has evolved," he said.
"Water recycling is a reliable, proven technology that has been used safely around the world for more than 40 years."
He said the company had consulted local communities, elected representatives, regulators and stakeholders since 2022, with feedback helping shape the proposals.
Under the current approved plans, the reservoir will store spring water and be able to supply up to 21 million litres of water per day.
A spokesperson for Portsmouth Water – which is building and operating the new Havant Thicket Reservoir – said: "The Hampshire Water Transfer and Water Recycling Project is a separate scheme being developed by Southern Water and is subject to approval through the Development Consent Order process.
"If approved, the addition of recycled water would enable the reservoir to supply a further 90 million litres of water per day.
"We recognise that new solutions will be needed to help secure future water supplies. This is particularly important as we face increasingly unpredictable weather as a result of climate change, including hotter, drier summers, while also protecting the environment across the South East.
"Our focus remains on successfully delivering Havant Thicket Reservoir, which will play a key role in improving water resilience across the region and supporting local chalk streams by providing an alternative source of water."
Southern Water says recycled water would undergo multiple advanced treatment stages before entering the reservoir and would then receive further treatment before being supplied to customers. The company says all drinking water would be required to meet stringent UK standards and the project would be regulated by the Drinking Water Inspectorate, the Environment Agency and Ofwat.
The company says the scheme could provide up to 90 million litres of additional water each day during periods of drought by making use of Havant Thicket Reservoir's 8.7 billion litres of storage.
A spokesperson for the Regulators' Alliance for Progressing Infrastructure Development (RAPID) said: "Water recycling is needed as part of a diverse range of water supply and demand management options to ensure resilient water supplies and leave more water in the natural environment.
"The technology is a safe, established method of water treatment. It is proven to work elsewhere in the world, and we have a robust regulatory framework in place to support its application domestically.
"Our regulatory scrutiny of the Hampshire Water Transfer and Water Recycling Project through the RAPID gated process has involved several consultations, in addition to water company-led statutory and non-statutory consultations, where the public has had opportunities to input into the project's development.
"The Development Consent Order examination provides further opportunities for public engagement – and we would encourage local communities to engage with this process."