Top of main content

Our leakage performance

How we're tackling leakage

Every day we supply 2.6 billion litres of water, but not all of that gets to our customers. At the moment, we leak almost 23% of the water we treat – that’s enough to fill Wembley stadium each week.

We know it’s not acceptable to be losing so much precious water and we’re doing something about it. It’s not going to be quick, but we’re making progress and we’ve met our target for the last two years. Last year, we reduced the amount of water lost by 5.4%. Our aim is to reduce our leakage by 20.4% between 2020 and 2025.

What is leakage?

Leakage is lost water – that’s all the water not making its way to customers. Most of this water leaks from our ageing pipes, but sometimes it’s stolen or we’re just not as good as we should be in understanding how much water customers are using.

Leaks are caused by various things, including:

  • Old or weak pipes
  • Natural wear and tear on pipes
  • Sudden heavy traffic causing movement in the ground
  • Temperature changes, which cause pipes to swell and shrink
  • High pressure or sudden changes in pressure
  • Extreme weather events, like freeze-thaws.

Types of leaks

A diagram showing different types of leak.

Over 95% of leaks are never seen by customers. They’re often smaller, underground and harder to find. Visible leaks – the ones that do reach the surface – are larger, but they don’t lose as much water. This is because they’re reported to us and we start to fix them soon after they appear. Customer leaks are not on our network, but we work with our customers to repair them where we can. In some cases, we’ll do this free of charge.

Why reducing leakage matters

Water leaks can cause serious damage to homes and properties, and also have a big impact on the environment. As our population grows and climate change increasingly affects our lives, with hotter summers, colder winters and more rainfall, water will become even more precious. That’s why it’s really important that we protect our water supply and make it resilient for the future.

Reducing leakage is an important part of our wider plans to look after water. We’re also working with customers to help them save water and use it more efficiently – which helps reduce water and energy bills too.

We run smarter home and smarter business visits to help our customers understand how much water they use. Our water efficiency teams fit water saving devices and give personalised advice on how to save water. We’ve also installed over 500,000 smart meters to help customers track their water use.

What are we doing to reduce leaks?

New leaks appear all the time, so we need to work hard simply to maintain our leakage level and stop it from getting worse. So, we have to be really innovative in order to go further and reduce our overall leakage level each year.

We measure leakage in megalitres, or millions of litres, per day (Ml/d). One megalitre is equal to around 12,500 baths, or 40% of an Olympic swimming pool.

This year so far, we’ve stopped 171 Ml/d of water being lost. That’s the equivalent of 68 Olympic swimming pools.

How do we fix leaks?

Here’s our process:

  1. Locate: We’ll find a leak, or it’ll be reported to us.

  2. Assess: One of our leakage teams will assess the leak. They’ll check what needs to be done to fix it and also how urgent it is. We prioritise repairs based on things like the amount of water being lost, the effect on customers’ water supply, the complexity and the location.

  3. Plan: We’ll always plan the repair as quickly as possible, and in a way that’s least disruptive to our customers. However, it’s not just us who are involved in the process and it can take time to plan the work.

    We need to work with the council and highways authorities if we need to close a road, for example, and we need to make sure the right signage is in place to alert customers. Traffic management will be set up, so we can work safely in the road to fix the pipe. We also send letters to customers near the site, so they know what’s going on. This is particularly important if it’s going to disrupt their supplies, create noise, or affect access to roads.

    Sometimes we have to balance whether it’s better to do the repair during the day or at night. Closing roads at night helps us to avoid disrupting traffic and water supplies during the day. However, repairing pipes at night may create noise when customers are sleeping.

    We sometimes need to work with other utilities too, so they know we’re working near one of their pipes and they can take the right safety precautions. We have to be especially careful when working near railway lines and work closely with National Rail when we do.

  4. Repair: Once the plan is in place, we’ll send a repair team to fix the leak. This might involve turning off the water or redirecting water around other pipes, either underground or above ground. Sometimes the repair teams need to dig down to the pipe by hand, particularly if it’s in a tricky position and surrounded by other utility pipes like gas mains. This takes a lot longer than using machinery but is the safest way. When the pipe has been fixed, we resurface the road which can take time to set safely.

Did you know that some of our pipes are up to 3 metres underground?

How can you help?

You can help us find leaks and save water. If you spot a leak, please let us know.

Report a leak online

You can also help us by:


The information provided is, to the best of our knowledge, accurate, but may be subject to change from time to time. The information does not represent formal annual regulatory reporting.

safe spaces
Together we can end domestic abuse