Background: Why are we replacing pipes?

Because more than a third of London's water mains are over 150 years old - and more than half are over 100 years old - we now face a massive challenge in preventing leakage.

Although we have made major investment over the past ten years, water pipes in many areas of London are still among the oldest in the United Kingdom. They need replacing.

This work is particularly important as London's water resources are being put under increasing pressure from the effects of climate change, population growth and rising demand for water.

We're committed to replacing more than 1,000 miles of water mains by 2010.

Although the original cast-iron mains have served us well, due to an increase in road traffic and ground movement, they are now more likely to leak, or even burst.

We are therefore targeting the areas where the mains are the oldest and leakiest, and replacing the old pipes with new plastic ones that are more durable and flexible.

Although the work inevitably involves some short-term disruption, it will bring many long-term benefits, most importantly a reduction in the potential for future bursts and leaks, minimising the need for more streetworks.