Life cycle of leak

Leaks can happen for a variety of reasons. Find out what causes them and how we fix them.

What we do

Once a leak is reported, our engineers are dispatched to identify the cause and arrange the necessary repairs.

Our target is to fix 80% of leaks within five days and all leaks within 10 days – subject to authorisation from the Highways Authority where we need to dig in a road or public footpath.

Any leak considered an emergency to our network will be repaired with the highest priority. Other significant leaks are often repaired within 24hrs.

Every day we actively survey and repair our water network to minimise the chances of future leakage. Additionally, we frequently upgrade our network to plastic pipes to protect water supplies well into the future.

We have one of the lowest levels of leakage in the country. In the last year our staff found and fixed over 15,000 leaks and a further 10,000 reported by our customers.


How do leaks happen?

Temperature changes (such as extreme cold and prolonged dry spells) can cause the ground to move – putting strain on our underground water mains and causing them to leak.

Illegal standpipes, high commercial water use and other industrial misuse can lead to unexpected pressure surges in the water mains, which can also lead to bursts.

Many of the pipes within our water main network are metal (generally cast iron). These pipes have stood the test of time but are starting to show their age.

Our mains replacement programme aims to replace the older pipes with plastic pipes to protect water supplies well into the future.


Worried about your bill?

If the leak you have spotted is on our pipe work and before the meter, this won’t affect your bill.


What’s groundwater?

Groundwater refers to any water found beneath the surface, filling pores or cracks in soil and rocks.

When rain falls, some runs off directly over the surface into rivers, streams and drains, some evaporates and some is taken up by plants. However, a significant proportion of the rain falling across the South East is absorbed by the earth and seeps into deeper layers of soil and rock below the surface.

At a certain depth, the soil and rock will become soaked with water rising back to the surface. It can often be very difficult at this point to tell the difference between groundwater flooding and flooding from other sources.

When investigating, our inspectors carry out extensive tests on all pipe work and test the water to identify its source. If it is groundwater flooding, your local council is the lead authority. The Environment Agency holds overall responsibility for management and monitoring of groundwater.

Life cycle of a leak


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