Londoners should save water by flushing the loo less, or they could see standpipes in the streets by next summer, mayor Ken Livingstone has warned.
"If all you've done is take a pee, you don't need to flush the toilet every time," he said at a press conference yesterday.
Water use in the capital is higher than the UK average of 150 litres per person in a day, he added.
Each Londoner uses about 165 litres of water compared to 120 litres in European cities like Copenhagen and Berlin.
Hosepipe and sprinkler ban
Mr Livingstone said he would ask the government this Friday for powers to make a drought order banning the use of hosepipes and sprinklers in the capital.
The restrictions could apply for most of this year, and are likely to be repeated annually during dry summers.
Each Londoner uses about 165 litres of water a day. If you had to fetch it from a well, you would have to carry over 18 buckets of water home.
The mayor also wants to bring in "compulsory water metering", which has reduced consumption in other cities by six to ten per cent.
The UK and Ireland are the only European Union member states without water metering, he said.
London drier than Ethiopia
The past eight months were the second driest since weather has been recorded, the mayor added.
"Were we to have another dry winter, then by next summer standpipes would be in greater use across London."
The Thames region saw only a quarter of its average rainfall in June.
By the end of the decade, the capital's water demand will outstrip its supply by six per cent, Mr Livingstone warned.
London has developed a "unique micro-climate" that is the driest and hottest in the entire UK. "We get less water fall in this city than in the capital of Ethiopia, Addis Ababa."
Most water flushed away
The mayor said a third of the water used in London households is flushed down the toilet.
"Don't use a sprinkler or hose in the garden, don't use a hose to wash your car and don't flush the lavatory if you just had a pee.
"In one hour a sprinkler uses more water than a family of four uses in a whole day."
The 1,100 litres it disperses each hour equals 122 buckets of water.
Mr Livingstone also urged Londoners to shower, which takes about 30 litres of water in five minutes, rather than bath in 90 litres.
"These policies have already been adopted in the mayoral Victorian home."
Leaks to fill 1,000 pools
But Liberal Democrat environment spokesman Mike Tuffrey said the mayor ignored the fact that enough water to fill nealry 1,000 Olympic-size swimming pools was lost through leaky pipes every day.
"While steps to reduce demand for water, such as compulsory water meters, are welcome, the approach to solving this problem must be led by the water companies.
"Advising people to put bricks in their toilets to save water is one thing, but to tell people not to flush the toilet after spending a penny will just pee off Londoners."
Conservative environment spokesman Roger Evans added: "If the issue of water usage is so great that we have to consider such unappealing solutions then why has the Mayor waited so long to act."
A major advertising campaign, to run for years, will remind people to take these steps.
"It's a wake-up call," the mayor said. "We can't carry on using water on this basis."