Under plans being considered by Thames Water, Londoners could be drinking recycled toilet water in a bid to tackle a looming water shortage in the capital.
London residents are being asked by the company for their views on the idea of drinking sewage water that had been treated, put back in the Thames or another river and then retreated.
Local people are being asked by MPs, including Europe minister David Lidington, to respond to the consultation.
Key to whether the proposal went ahead was whether Londoners were happy with such a water supply - or revolted by knowing its origins, even after being reassured by scientists about its quality and safety.
London would face a growing water shortage as the population increased towards 10 million.
Unless action was taken, the deficit would be 2 per cent, or 125 million litres a day by 2020, according to Thames Water's draft long-term strategy 2015-2040. It would increase to 16 per cent or 367 million litres per day by 2040, which was the need of 2.2 million customers.
Thames Water is now investigating wastewater recycling, including from dishwashers, washing machines, baths and toilets to turn into drinking water.
The company is seeking the views of the public on the proposal as part of its consultation on its five-year-plan.
Thames Waters says in its strategy document: ''One possibility (to cope with demand) is 'wastewater recycling'.
''This process is already common practice in many parts of the world.
''It involves putting treated effluent from a sewage works through a further process which would allow the water to be returned to a river at higher than usual quality and pumped out again downstream.
''It can then be treated to drinking water standards and put back into supply, rather than lost to the sea.
''We need to carry out further research into this approach, and will be doing so over the next five years.
''Other potential solutions which we will be examining closely include a new storage reservoir and transfer schemes to bring water from other parts of the country.''
It added: ''Long-term predictions suggest we will need a major new source of water by the late 2020s, and that this is an issue which also affects the wider South-East area.
''Potential solutions will take a long time to plan and implement. We therefore need to work with stakeholders, regulators and other water companies over the next five years to agree on the best course of action.''
The consultation asking customers for their opinions on all aspects of the company's service would run until 26 June.