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 the UK 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 volume of water we put into supply against the estimated volume 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, so these targets are for average daily leakage. Our actual levels can be compared with our targets in the table below.
|Annual leakage target (Ml/d)||649||630||620||612||606|
|Actual annual leakage level (Ml/d)||642||677||TBC||-||-|
|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 leakage target of 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
Our December 2018 results
Leakage levelThe graph below shows the actual amount of water lost from our network in December 2018, compared with our plan. In December our leakage level was 717 Ml/d, which is 15 Ml/d more than we’d planned. This represents a marked narrowing of the gap between the actual and planned levels of leakage in comparison to November, when our average leakage level was 62 Ml/d more than we’d planned. This change is due to the combined effect of higher than planned leak repair activities and the benefit of the relatively warm conditions in December. This milder weather puts less stress on our pipes, resulting in lower levels of leakage.
We believe that the higher than planned leakage level that we have experienced over the last 9 months was due to the combination of the cold weather we experienced in March 2018, and the prolonged hot and dry weather we experienced over the summer. In broad terms, the cold weather had two effects – leakage rose because more bursts occurred, and even though we fixed a lot of the extra leaks it meant we started the year with more leakage than we planned – so we have to work harder to catch up. 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 are committed to doing all we can to address leakage and aim to start 2019/20 with leakage at a level that helps us meet our 2019/20 annual leakage target.
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
Customer leaks - these are within the boundary of a customer’s property
Finding and fixing hidden leaks has the biggest impact on reducing leakage. When we find a hidden leak, we don’t always know how big it is until we’ve dug the hole and fixed it.
The pie chart shows the split of the different types of leaks that we fixed in December 2018. 49% were hidden and had to be detected by our teams. 20% 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 31% 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 December 2018. We averaged 1,248 each week, and this represents the 12th month running in which we have out-performed our original plan. 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.
The graph below shows the estimated volume of water saved from fixing leaks in December 2018, compared with our plan. This includes hidden leaks and the customer-side leaks we fix. We stopped leaks which we would estimate to reduce leakage equivalent to 31 Ml/d of water in December, which was 7 Ml/d more than we had originally planned.
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 reach our target by 2019/20, we also have additional leakage reduction activities taking place.
- 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 have a detailed review of our leakage reduction plan 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 planned. 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 have established a dedicated Leakage Task Force. 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 impact leakage. In order to mitigate this risk, we continue to review and update our leakage 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.
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 performanceDownload the pdf below to learn more about our leakage performance
How can you help?
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.
- Learn about the impact of the weather on the water network
- Learn about our metering programme
- Jargon buster
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.
Feedback: We welcome your feedback on our leakage performance information. Get in touch with your feedback.