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 we're reducing leaks
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How do we fix leaks?

Here’s our process:

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

Getting leaks fixed at home – here’s our guide on fixing a leak at your property
Saving water by being ‘water smart’
Preparing your home for winter by protecting your pipes
Tracking your water use with a smart water meter

Highlights from the last quarter: July – September 2021

We’re on track to meet our target.

Leakage over the period from April 2021 to September 2021 was 562 Ml/d, 7 Ml/d better than our internal target
Between July and September, we fixed 13,527 leaks and prevented 93 Ml/d of leakage

What’s our leakage level?

We estimate leakage each day by comparing the volume of water we put into supply against the amount we estimate is being used. We take leakage measurements at night between 3am and 4am, when water usage is lower and more constant.

Leakage levels change throughout the year, so to measure and report our performance we take our daily leakage figures (in Ml/d) and average them for each month and in turn across the year.

The graphs below show the estimated amount of water lost from our network this year compared with the forecasts in our leakage reduction plan.

A graph showing the average monthly leakage against our plan

This shows the monthly average leakage we’ve achieved, and the monthly average leakage level we would expect if we deliver our leakage reduction plan.

A graph showing year-to-date leakage against our plan

This shows the average of our monthly leakage levels from April to date and our forecast. This is known as the year-to-date average.

The solid blue line – our reported leakage – shows our actual leakage level, based on our operational data. The dotted lines show our forecast leakage level if we deliver our plan. Together, these three lines represent three bands:

The central band (the dotted blue line) shows where we expect leakage to be if everything works out as we initially predicted
The upper and lower bands (the orange and green dotted lines) reflect the possible impact of risks to our plan. These risks might include adverse weather, or weather that’s milder than we expected. Our plan might also be affected by finding more or fewer large leaks than we predicted.

This year, our average monthly leakage levels have reduced each month. Although our leakage level at the start of the year was above our mid-range forecast (the dotted blue line), it reduced sharply from April to June – which is what we’d expect during the warmer summer months as there’s less stress on pipes. The leakage level has continued to reduce during July and September, although the rate of the reduction has slowed which is what we would expect at the end of the summer period.

Leakage performance has been helped by outbreaks of visible leaks being 7.5% below forecast for the July to September period, and 6.5% below forecast since the start of April 2021.

How much water is that?

A leakage level of 526 Ml/d is about 20% of the total water we supplied (based on our 2020/21 supply). It’s equal to 210 Olympic swimming pools full of water.

How many leaks have we fixed?

We fixed 13,527 leaks between July and September 2021 – which is below the 17,775 that we’d planned to do. This was equal to 1,041 leaks on average each week. We’ve fixed fewer leaks than we’d planned to due to the challenges of Covid-19 and market conditions, which have both had an impact on resources. As a result, we’ve been working smarter by using innovative technology and prioritising larger leak repairs.

By making these repairs, we estimate that we prevented leakage equivalent to more than 71 Ml/d of water over the quarter (19 Ml/d below our plan of 90 Ml/d) . This is the volume of water saved based upon fixing non-visible and customer leaks. We don’t include visible leaks because they’re not considered to reduce the underlying level of leakage.

Our leakage reduction activities (including our pressure management and water efficiency initiatives) saved 93 Ml/d compared to a target of 108 Ml/d between July and September.

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.

Risk	Impact	Mitigation
Weather	This is usually the largest risk to our leakage level each year Both extreme cold and hot conditions can increase leakage and with the impact of climate change, the risk is increasing	We continually review and update our leakage reduction plans against a range of short and long-term weather scenarios We formally review our plans every three months to assess performance, identify areas where we need to do more, and review resource needs
Ongoing impacts of Covid-19	Fewer teams available to make repairs, so we’re not able to repair as many leaks as planned Working from home means that demand patterns are still changing	We’re working with our delivery partners to increase our resources, and we review our plans quarterly to make sure we remain on track We’re using more smart meter data to better track and understand water use