Our leakage performance

Headlines for January 2019

  • In January 2019, we fixed 20% more leaks than we'd planned and we're ahead of our leakage reduction plan for the month
  • While our January 2019 performance is encouraging, overall we are still behind our leakage reduction plan for 2018/19
  • We have created a Glossary of Terms to accompany our monthly reports and ensure transparency

What is leakage?

Leakage is the amount of water lost from pipes across the water network. We supply almost one 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 use a set period of the night for this measurement, because we know that is when customers' water use is at its lowest. 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 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 - -

The table shows we beat our target in 2015/2016 but missed it in 2016/17 and in 2017/18.

We’re committed to reaching our 2019/20 target to reduce leakage to 606 Ml/d and have a plan in place to get us there. We have also committed to reducing leakage by 15% by the end of 2025 and by 50% in the longer term.

How do we measure monthly results?

Our monthly results are broken down into three areas:

  • 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

Over the last few months, we have been working to review and refine the estimated volume of water saved from our 'Find and Fix' activities. This is covered in further detail later in this report.

Our January 2019 results

Leakage level

The graph below shows the actual amount of water lost from our network in January 2019, compared with the forecast in our leakage reduction plan. In January our leakage level was 732 Ml/d, which is 17 Ml/d less than we’d expected. This is the first month in the 2018/19 reporting year that we are ahead of our recovery plan, which means less water was lost as a result of leaks during the month than we had forecast. This change is due to the combined effect of higher than planned leak repair activities and the benefit of January being, on average, warmer than typically expected. This milder weather puts less stress on our pipes, resulting in fewer leaks.

Leaks performance graph of water lost for November 2018

While our performance in January in encouraging, our average leakage level for the 2018/19 reporting year as a whole is still higher than in our leakage reduction plan. We believe that this is due to the combination of the cold weather we experienced in March 2018, and the prolonged hot and dry weather we experienced last summer. In broad terms, the cold weather meant leakage rose because more bursts occurred. In addition, even though we fixed a lot of the extra leaks, it meant we started the year with more leakage than we had forecast – so we have to work harder during the year to catch up. It’s like running a race but starting from well behind the starting line. Following the cold weather in March 2018 (also known as Freeze/Thaw), we published a report on how we plan for, manage and respond to incidents.

The hot, dry weather had two effects – first, higher demand for water meant we increased the amount of pumping needed to maintain storage levels in our reservoirs. This increased pressure in the pipes which in turn increased the amount of water lost from existing leaks and meant new leaks happened. Second, the very dry ground shrinks around the pipes, which can cause them to move and lead to more bursts and underground leaks.

To improve our current performance, we have established a cross-business Leakage Task Force to focus additional resources and expertise in order to maximise the certainty of delivering our leakage targets on a sustainable basis.

We remain committed to doing all we can to address leakage and are striving to start 2019/20 with leakage as low as possible, to help us meet our 2019/20 annual leakage target.

Leaks fixed

We fix three different types of leaks:

Visible leaks- these are easy to see, for example on pavements or roads

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

Customer leaks - these are within the boundary of a customer's property up to the point where the pipe enters their home/building

The pie chart shows the split of the different types of leaks that we fixed in January 2019. 46% were hidden and had to be detected by our teams. 24% 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 30% were customer leaks; we work with our customers to repair their leaks free of charge.

Total number of leaks fixed

The graph below shows how many leaks we fixed in January 2019. We averaged 1,582 each week, and this means we have out-performed our original plan every month since January 2018. We have achieved this significantly 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.

Reducing leakage

The graph below shows the estimated volume of water saved from fixing hidden and customer-side leaks in January 2019, compared with our plan. We repaired leaks which we estimate to have prevented leakage equivalent to 45 Ml/d of water in January, which was 9 Ml/d more than we had originally planned. 

Our Leakage Task Force is currently assessing the way we estimate the volume of water saved from 'Find and Fix' activities. The initial indications from this work suggest that, in growing our Find and Fix activities, the estimated water savings we have historically relied on may be over-estimated. The Task Force is working to verify this. We will share our findings and, depending on the outcome of this review, we will update our estimated volume of water saved figures for previous months.

For clarity, the graph below is based on our current estimated volumes of water saved per leak.

Our leakage reduction plan

Finding more leaks to fix

Fixing leaks is the most important activity to reduce leakage. To fix more hidden leaks, we need to find them on our pipe network. We’re increasing the number of leaks we find through:

  • 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 have now 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 now have more leak detection technicians working for us than ever before. They use data to judge where leaks are occurring and tell repair teams where to dig. As a result, we have found significantly more leaks in 2018/19, to-date, than over the same period the previous year.
  • We’re also testing innovative solutions such as using thermal imaging cameras attached to drones, infrared cameras on an aeroplane and high resolution satellite images.

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.

Reviewing and refining our plans

To make sure that we’re on target to recover leakage and meet our target in 2019/20, we monitor our performance weekly and review our leakage reduction plan in detail every month. The cold weather in March 2018 meant that we started the 2018/19 reporting year with more leaks on our pipes and therefore higher leakage than we’d forecast we’d start with. To help us recover from this, we’ve needed a revised plan to fix these leaks, on top of what we already had in place. 

We are now ahead of our plans to find and fix leaks, but this has not yet resulted in the leakage saving that we expected. Consequently, we established a dedicated Leakage Task Force which comprises industry experts from within Thames Water as well as experts from external parties. The aim of our Task Force is 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.

The biggest risk to us meeting our target in 2019/20 is the weather. As detailed above, both extreme cold and hot conditions can increase leakage levels. In order 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 addition, we have prepared a winter contingency plan that allows us to adapt operational responses to weather conditions. This ensures focus is maintained on activities that prevent leaks and maintain customer supplies.

Other material risks that we monitor are the effectiveness of our leak measurement models and the leakage due to factors other than weather effects. The Leakage Task Force we established in November is addressing this and other questions to ensure our planning assumptions and leakage reduction strategy are effective. The Task Forces comprises industry experts from within Thames Water as well as experts from external parties. The work of the Task Force will further help us refine our plans for 2019/20 with the aim of delivering the required output even under conditions where burst rates increase beyond the normal anticipated level. 



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 us today.

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 first 6-monthly review of our compliance against our Undertakings to Ofwat on 31 October and the next one is due on 1 May 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.