Thames Water pulled the chain on the mayor's plan

He wanted the firm to tell people not to flush when they "take a pee" - to cut down on the third of all water in homes which is flushed down the loo.

But, he told Labour's conference, the idea was rejected by the firm, who had told him its German owners did not like to talk about such things.

"So you can't mention the war or flushing the toilet," he joked.

Mr Livingstone was speaking during a debate on the environment at Labour's conference in Manchester.

Obviously we encourage people to save water, but it really is up to the individual how often they want to flush their toilet Spokeswoman Thames Water

He said his plan would not only save water, but the costs of purifying the waste product.

"A third of all the water that comes into our homes is flushed down the loo and you really don't need to flush the toilet when you've just had a pee," he said.

But, he said, Thames Water did not like the proposal: "They said 'we've got a German management and they don't like to talk about these things."

However, a Thames Water spokeswoman said she did not recognise the remarks about the company's bosses.

"I would find that very, very unlikely," she said.

'Personal choice'

She said the organisation was run by German multi-utility company RWE, but they were in the process of being sold.

"Obviously we encourage people to save water, but it really is up to the individual how often they want to flush their toilet," the spokeswoman said.

"It is not for us to advise on their own living conditions."