Thames Water has already been given the green light by Mr Reed to build a water recycling plant at Teddington, west London, which would treat sewage from the Mogden Sewage Treatment Works in Isleworth before pumping it back into the river. The plan was designated an NSIP in January under the previous government.

Treated wastewater will be used to replace water drawn from the river to maintain full reserves in drought situations.

The plans have been opposed by Richmond Council, which claims it could have a negative impact on water quality and local open spaces.

Activists argue that wastewater treatment does not remove pollutants such as chemicals forever or microplastics, which could threaten biodiversity on stretches of the river.

Launching a major review of the water industry this week, Mr Reed warned of the need to increase supply.

“By the mid-2030s, if we don’t take steps to increase water supplies – reservoirs as well as infrastructure – then the demand for drinking water will start to outstrip the supply, in a way that is already happening in some Mediterranean countries,” he said. he said.

“We cannot allow the water system, the water sector, to continue in this way.”

A Defra spokesman said: “Our water infrastructure requires significant investment and development to secure supplies as we adapt to climate change and a growing population and to help grow the economy.

“All nationally significant infrastructure projects need development consent under the Planning Act 2008 before schemes can proceed, which ensures proper consultation with local communities affected by a new scheme before planning consent is sought development.”