Our leakage performance

Headlines for April 2019

  • April is the first month of our 2019/20 reporting year. Our average leakage level for the month was 637 Ml/d, which is in line with our leakage reduction profile.
  • We completed 7,074 leak repairs in the month, continuing to out-perform our plan.
  • We repaired leaks which we estimate have prevented leakage equivalent to 40 Ml/d of water in April, which is 1 Ml/d more than our plan.

What is leakage?

Leakage is the amount of water lost from pipes across the water network. We supply almost a third of the water used by people and businesses in England and Wales each day, to ten million customers, through over 32,000 km of water pipes.

How do we measure leakage?

To calculate our leakage figure, we employ an industry-standard method which all water companies use. This method compares the measured volume of water we put into supply against the volume we estimate our customers are using. The difference between these two values is what we record as leakage. We also take water pressure into account, as this affects the amount of water lost through leaks.

We measure leakage in millions of litres per day (Ml/d). As an idea of scale, an Olympic-size swimming pool (50m x 25m x 2m) contains 2.5 million litres of water.

What’s our target and how are we doing?

We’ve set annual leakage targets up to 2020. Leakage levels change throughout the year, therefore 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. Our actual levels can be compared with our targets in the table below:

  2015/16 2016/17 2017/18 2018/19 2019/20
Annual leakage target (Ml/d) 649 630 620 612 606
Actual annual leakage level (Ml/d) 642 677 TBC - -
  2015/16 2016/17 2017/18 2018/19 2019/20
Annual leakage target (Ml/d) 649 630 620 612 606
Actual annual leakage level (Ml/d) 642 677 695 690* -

 *The 2018/19 leakage level is a provisional figure and is subject to year-end verification and audit.

The table shows our performance for the last 4 years. The results have been externally audited and confirmed, apart from our 2018/19 performance, which is currently in the final stages of audit. While 690 Ml/d is well above what we would have liked, it does reflect a very challenging year in terms of weather conditions.

We remain committed to doing all we can to hit our target of 606 Ml/d in 2019/20. Our plans include the amount of work we need to do to deliver this target. While we’re doing everything we can, we recognise that achieving 606 Ml/d will be a significant stretch. This is due to starting 2019/20 with leakage at a higher level than we’d have liked, as well as the inherent challenge in reducing leakage below our all-time lowest level. When taking these risks into account, we believe 636 Ml/d is a more realistic leakage forecast for 2019/20.

Despite the above point, leakage reduction remains one of our top priorities. We continue to strive to deliver our 606 Ml/d target and we keep stakeholders updated about our leakage performance and forecasts.

We also remain committed to reducing leakage by 15% from our 2019/20 target level by the end of 2025 and by 50% in the longer term.

Our April 2019 results

We've agreed with Ofwat that, as part of reporting our monthly results, we will provide details on:

  • Leakage level - the estimated amount of water lost each day
  • Leaks fixed - the number of leaks we find and fix
  • Leakage reduction - the estimated volumes of water saved from leaks found and fixed

Leakage level 

The graph below shows the actual amount of water lost from our network in April 2019, compared with the upper and lower forecasts in our leakage reduction plan. In April our leakage level was 637 Ml/d, which is in line with our leakage reduction plan. This is a result of our continued efforts to find and fix leaks, aided by the continued milder than average conditions.


Leaks performance graph of water lost for March 2019

Leaks fixed

We fix three different types of leak. On average:

About half are hidden leaks - these are below the surface and aren’t easy to find. We find them using data, technology, and people. Fixing hidden leaks has the biggest impact on reducing leakage.

About a quarter are visible leaks - these are easy to see, for example on pavements or roads.

About a quarter are customer leaks - these are within the boundary of a customer’s property up to the point where the pipe enters their home/building.

In April 2019 55% of the leaks we fixed were hidden and had to be detected by our teams and 22% were visible and were reported by the public. We prioritise fixing visible leaks in response to customer expectations and fix them on our biggest pipes first wherever possible. The remaining 23% were customer leaks, where we work with our customers to repair their leaks free of charge.

The graph below shows how many leaks we fixed in April 2019. We averaged 1,415 each week, and this means we have out-performed our original plan every month since January 2018. We have achieved this higher figure by recruiting more people to fix leaks, making improvements to our planning processes and using state of the art leak detection equipment to help us find leaks.

Leakage reduction

The graph below shows the estimated volume of water saved from fixing hidden and customer-side leaks in April 2019, compared with our plan. We repaired leaks which we estimate to have prevented leakage equivalent to 40 Ml/d of water in April, which was 1 Ml/d ahead of our plan to bring leakage below its lowest ever levels by March 2020.


Our leak reduction plan

Performance against our plan

Our efforts, aided by mild weather in March, meant that we finished the 2018/19 reporting year with a slightly lower annual average leakage level than the 2017/18 reporting year. As we enter the final year of our current 5-year planning cycle, we have seen a continued improvement over the first month of the reporting year (April 2019), with our performance being in line with our plan.

To improve our performance, in November 2018 we established a dedicated Leakage Task Force, comprising industry experts from within Thames Water as well as experts from external parties. This cross-business Task Force is focusing additional resources and expertise to maximise the certainty of delivering our leakage targets on a sustainable basis.

The Leakage Task Force has been asked to review all the information we hold on leaks and our pipes and use this to predict where leaks are occurring, gauge the effectiveness of our repairs and how customer consumption patterns affect leakage levels. It is also working to increase our understanding of how our network performs and reacts in different weather conditions.

We remain committed to doing all we can to address leakage and to achieve our 2019/20 target. In the meantime, we maintain a dialogue about our leakage reduction plan with our key stakeholders.

Innovation in finding leaks

Fixing leaks is the most important activity we undertake to reduce leakage. Because fixing hidden leaks has the biggest impact on reducing leakage, we prioritise them. But, to fix more hidden leaks, we first need to find them on our pipe network. As we work to reduce leakage below our all-time lowest level, we have to be increasingly innovative in how we do this.

In 2018/19 we did this by:

  • Customer water meters - When we install a customer meter, we can immediately identify if there’s a leak. Our programme to install smart water meters is the second largest in the world and will help protect future water supplies.
  • Installing acoustic loggers - Acoustic loggers listen for the noise water makes as it leaks from pipes. They help us to improve leak detection and find harder-to-locate leaks. We installed approximately 26,000 loggers and are repairing the leaks located as a result of the information that the loggers are generating.
  • More leak detection technicians - We increased the number of leak detection technicians working for us to record levels. They use data to judge where leaks are occurring and tell repair teams where to dig. As a result, we found significantly more leaks in 2018/19 than the previous year.

This year we’re increasing the number of leaks we find through:

  • Addressing ‘Dead Zones’ - We’re mapping zones where it’s difficult to hear leaks using traditional techniques. We’ve also started a project to look in detail at 50 km of dead zone so we can find the best solutions to them.
  • Using temperature analysis - Working with a number of other water companies, we’re in the early stages of developing an innovative leak detection method that aims to use temperature data to pinpoint areas with larger leaks that are difficult to hear.
  • Improving identification of customer leaks - Leaks on customers’ pipes make up a significant proportion of our leakage, but the programme for detecting and repairing them often generates false alarms and unnecessary customer calls. We’re trialling a device to see if its method of quantifying customer leaks gives lower false alarms.

Leakage reduction activities

To help us reach our target by 2019/20, in addition to leak repairs we have additional leakage reduction activities taking place. These activities are intended to generate a sustainable reduction in our leakage levels and they include:
  • Pressure management - We manage the water pressure within parts of our network to reduce the likelihood of pipes bursting. This also reduces the amount of water lost through existing leaks.
  • Mains replacement - We have a long-term programme of replacing or repairing worn pipes, and we prioritise the ones which may cause most disruption if they burst or leak.
  • Accounting for all water used - We're continually trying to improve our estimate of water used from our network. This activity focuses on stopping illegal use (for example unlicensed standpipes and illegal connections), replacing faulty customer meters, and ensuring all properties are registered on our billing system correctly.

Risks to our plan

The biggest risk to us meeting our target in 2019/20 is the weather. Both extreme cold and hot conditions can increase leakage levels. To mitigate this risk, we continue to review and update our leakage reduction plans against a range of short- and long-term weather scenarios. This work enables us to review the resource requirements and ensure they are sufficient to repair the number of leaks required.

In March 2019, we announced that our Chief Operating Officer, Lawrence Gosden, would be leaving Thames Water in July 2019. As head of our operating division, Lawrence’s experience and leadership has been critical in driving improvements in our leakage reduction work. A succession plan has been put in place and this will result in a controlled handover of Lawrence’s responsibilities in the lead up to his departure. We’re confident that this will address any risk of the loss of continuity in leadership for our operational teams.

Other material risks that we monitor are the effectiveness of our leak measurement models, our understanding of how our pipes react to rapid changes in weather, and our ability to pre-empt network deterioration. Our Leakage Task Force is addressing these and other questions to ensure our planning assumptions and leakage reduction strategy are effective. The work of the Task Force will further help us refine our plans for 2019/20.

More information on our leakage performance

Download the pdf below to learn more about our leakage performance

How can you help?

Feedback: We would like your feedback on our leakage performance information. Please get in touch with your feedback.

We’ve also started a conversation thread on our community platform to create further opportunities for you to talk to us and to each other, and share ideas on reducing leakage. We’re keen to engage with you in a meaningful way and we intend to use your feedback to improve our understanding of how leakage affects you, so that we can adapt our services to better meet your needs.

Conclusion of Ofwat investigation – June 2018

Ofwat has investigated our leakage performance. In order to improve our management of leakage reduction, in August 2018 we agreed a package of financial and non-financial commitments with Ofwat under Section 19 of the Water Industry Act 1991. We refer to these as our Section 19 Undertakings. 

As part of our Section 19 Undertakings we agreed to pay £120 million back to our customers. This money will come solely from Thames Water’s shareholders and will be reflected in customer bills up to 2025. In order to clarify and improve how we report leakage we appointed Victoria Borwick, former Deputy Mayor of London and former MP, as an independent monitor of our monthly leakage reporting. Victoria brings highly relevant experience of reporting and communicating complex matters to the public. We are working with Victoria to provide external and independent feedback and challenge to how we engage with and improve customer understanding of our leakage targets and performance against these. 

In addition, we appointed John Gilbert to fulfil the role of Undertakings Compliance Officer. This role is responsible for ensuring overall compliance with the Undertakings and providing regular updates to our Board and Ofwat. We provided our second 6-monthly review of our compliance against our Undertakings to Ofwat on 26 April and the next one is due on 1 November 2019.

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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.