Engineers said today that water privateers have drained Britain dry despite the recent wet weather.
The GMB union, which represents utilities workers, urged MPs to call companies to account for selling off the country's reservoirs - infrastructure that could have helped ease this winter's drought.
Enviroment Agency officials warned in April that the south-west of England and Midlands were in drought, with it likely to continue at least until next year.
Yet this week's spate of flash floods are ironically a symptom of the drought, with hard-baked soil unable to soak up the sudden downpour.
GMB blamed water profiteers for the crisis, saying less than one per cent of Britain's rainfall actually ended up in tanks.
Thames Water has closed 25 storage facilities in England's south-east, the union said, leaving rainfall to run off into the sea - in a region where hosepipes have been banned twice in six years.
National secretary for water Gary Smith said he could not stress enough that Britain had no shortage of water, just a shortage of competent management.
"Storage and transfer are two of the main elements of water resource management - one to move water from times of plenty to times of shortage, the other to convey water from places where it is plentiful to areas where it is in short supply."
Water was a natural monopoly, Mr Smith said, but the government insisted on a "nonsense policy" of privatisation.
"Since 1990 Thames Water has paid out £5 billion in dividends to shareholders, raised from households, that should have been used to divert water into south-east and eastern England."
He urged Parliament's environment selcet committee to call Thames Water, its competitors and regulators to account.
A Thames Water spokesman said many closed sites had stored only small amounts of treated water, while others were only treatment plants.
The sites had been shut down because they weren't needed, he claimed.