By Dan Bell BBC News, London

Mr Pisula has been laying pipes in 100 metre sections for two years

Carlton Road in Walthamstow is an obstacle course of metal fencing, work vans, and reinforced plastic sheets covering trenches cut into the pavement.

This is the scene being repeated across London as the vast undertaking to replace the city's 100-year-old water mains grinds its way forward road by road.

You would expect London's inhabitants to meet the upheaval with grudging acceptance at best. At worst, with barely contained fury.

But if the work on Carlton Road is anything to go by, the new pipes are actually going down with a dose of neighbourliness and community spirit, and with lots of cups of tea.

Half way down the street a door swings open in one of the houses and a smiling girl steps out into the rain with a tray of tea and biscuits.

She hands it to one of the workmen, who has popped up out from one of the deep holes in the street, and steps back in side.

LONDON'S PIPE LAYING 550 miles of new pipe have been laid since 2003 Thames Water hopes to lay 1,000 miles of new piping by 2010 Currently there are 65 sites being worked on across London at a cost of �500,000 a day

Down in the hole Steve Pisula, 40, from Hitchin, in Hertfordshire, looks up with a grin to his friend with the tray. He has been working on the mains replacement project for two years.

"Every road we've worked on there's always been someone who's offered us a cup of tea, they're friendly people," he says.

The worst part of the job, he says, is not grumpy residents, but the fact that despite being in a hole in the rain with a broken water pipe, to fix the new pipes the joints have to be absolutely dry.

"On a day like this, with the mud and tools wet, it's so difficult," he says.

Further down the street, the men are getting an even warmer reception.

Street flirting

Another girl has been chatting with one of the workmen as she fills her kettle from the 1,000-litre bowser parked in the middle of the road.

Suddenly she comes running up the middle of the street, kettle in hand, and just before disappearing inside one of the houses, squeals: "I think I just pulled!"

Behind her, a young man in a high visibility vest strolls back to his workmates.

On door steps up and down Carlton Road, and on nearby streets as well, the story is much the same: residents say the workmen are polite and the work is being done with as little disruption as possible.

The new water mains are flushed through with chlorine

But there is more to mains replacement than tea and flirting.

London's cast iron water pipes, laid between 100 and 150 years ago, have been heavily corroded by the acidic clay that underpins the city's streets.

In some cases, when the workmen dig down they find there are no pipes left at all, and the water is running under pressure through channels in the clay.

Before the work began four years ago Thames Water said about 900 million litres of water a day was leaking away into the ground. This figure is now down to about 700 million litres.

Not everyone of course is as cheerful about all this disruption as the girls with tea tray and kettle.

It sounds like a washing machine is on full for two hours Frances Holmes

Another resident of Carlton Road, Frances Holmes, 37, a researcher for an investment bank, has just had her second child, Jacob, who is four months old.

She says the lack of water for the day is not as much of an inconvenience as the works that go around it.

She says pushing the buggy for her three-year-old son over the plastic hole covers is difficult, as is being forced to park several streets away.

Residents said they felt sorry for the men working in the rain

But worst of all is the noise from the road works, she says.

"They have to use cutting machines to open the road up and cut the holes, and it sounds like a washing machine is on full for two hours," she says.

"Any new mother is normally pretty wiped out at eight o'clock in the morning and would really rather go back to bed again."

"But there is no chance of going back to sleep in the mornings after being up in the night."

Fortunately for Mrs Holmes, by the following weekend the men will have moved on and the holes in the road will have been filled in.

But for London, the project still has a very long way to go.

By 2010, Thames Water hopes to put down another 1,000 miles of new piping.

But asked when the project in London will be completed, a spokesman for the water company said: "This is just the tip of the iceberg."