Britain's biggest water company announced today that it is imposing water restrictions for the first time in 15 years amid heightening drought fears.
Around eight million people in the Thames Water area, which includes Greater London, will be affected by the hosepipe and sprinkler bans from next month.
The move follows a prolonged period of below-average rainfall in the South East which has prompted the worst shortages in a century.
Restrictions have been in place for many parts of the region since last year, and the Environment Agency (EA) has warned that more drastic measures may be needed unless the situation improves.
Some areas of Kent and Sussex could even see standpipes introduced in the streets for the first time since 1976, or supplies cut at certain times of day.
Earlier this month ministers controversially granted Folkestone and Dover Water the power to install compulsory metering in homes it serves, and other firms are considering similar applications.
Jeremy Pelczer, chief executive of Thames Water, said today that he had not taken the decision to impose bans lightly.
"We are reluctant to restrict the amount of water our customers use, but the situation is serious.
"The drought across the South East has now gone on for so long that we have to be prudent and introduce measures that will make best use of limited supplies and help protect the environment."
Mr Pelczer said the move would "lessen the likelihood of more stringent restrictions later", but much depended on rainfall levels.
"If we see little rain, coupled with high demand, then we may have to go further and restrict a wider range of non-essential uses of water."
The company is currently spending £1 billion replacing Victorian pipes, which are estimated to leak around a third of water travelling from reservoirs to homes.
An advertising campaign encouraging the public to help conserve water is also being planned with the Greater London Authority.
Simple tips include not washing cars, not leaving the tap running while brushing your teeth, and having showers rather than baths.
A spokesman for the EA welcomed the move: "Given the current status of our water resources, water companies must take action to reduce risks to water supply and the environment.
"Thames Water is acting responsibly by introducing a hosepipe ban at this time."
The South East has been harder-hit by the drought than the rest of Britain because of its high population density, relatively low number of reservoirs, and geological factors including a heavy reliance on groundwater supplies.
Andrew Marsh, of the Consumer Council for Water, said imposing hosepipe bans now to prevent more serious problems in the summer was a "sensible precaution".
"Consumers will support the ban, but the problem with Thames Water is that they have a pretty poor record with leakage.
"There's a big perceptual problem there when down the road there may be a pipe leaking water."
Darren Johnson, chair of the London Assembly's Environment Committee, said: "We're no longer facing a crisis - it's arrived.
"We're taking our first step on the slippery slope that ends with water rationing, unless real and concerted action is taken now to address water loss through leakage."
But he added that Thames Water and the industry regulator, Ofwat, also had to take responsibility for ensuring leakage problems were addressed.
"Thames Water, Ofwat and the Government have got to agree a long-term investment strategy to repair and replace London's crumbling mains system as a matter of urgency.
"There is a real danger that the public will not heed official advice to stop wasting water if they continue to see the water company as the biggest culprit."Reuse content