Some parts of England will run out of water within the next 20 years unless "urgent action" is taken.
That's the view of the Public Accounts Committee (PAC) in a report on the state of water supplies.
It's calling on the government to establish a league table for water companies to pressure them into dealing with leaks.
It also wants efficiency labels on domestic products like washing machines and dishwashers to be made compulsory.
The government responded by saying it had already initiated a programme to improve performance in the water industry.
"One-fifth of our daily supply is wasted."
The PAC is accusing ministers and regulators of taking "too ponderous" an approach to improving infrastructure.
In their report, the MPs say the Department for Environment, Food and Rural Affairs (Defra) has shown a "lack of leadership" on the issue.
"Defra has failed to lead and water companies have failed to act," committee chair Meg Hillier MP said.
"We look now to the department to step up, make up for lost time and see we get action before it's too late."