Big question

BQ2 - How will we achieve zero leakage in a sustainable way by 2050?



Leaks from underground pipes are a reputational issue for all water companies.  Since 1997, leakage has been reduced by 40 per cent.  Even still, 20 per cent of all the drinking water produced is still lost – from companies’ pipes, homes and businesses.

Customers, regulators and Government expect water companies to reduce leakage much further.  In England and Wales, water companies have already started to reflect those expectations and pledged to reduce leakage by a further 461 million litres per day, or 16%, between 2020 and 2025.

Leakage Innovation Heatmap

This work has been carried out by Jeremy Heath of SES Water, in his capacity as the programme lead for Leakage Big Question. The purpose of this exercise was threefold

  1. To generate a UK industry-wide innovation heatmap for leakage, which captures the current research programmes.
  2. To assist in the development of the UKWIR Leakage Big Question, by identifying those areas where there is little research currently taking place.
  3. To foster collaboration between Companies by highlighting those areas where multiple companies are working on similar projects.

It is important to understand that the projects lists are not exhaustive and inter-company comparison on the levels of leakage innovation are not valid. Some companies have been unable to provide their full project list due to contractual or non-disclosure agreements. Some companies have listed projects separately, whilst others have grouped them together (for example smart networks). This exercise has only sought to capture a small segment of all of the innovative work being carried out by water companies, in order to develop research plans and promote collaboration on leakage innovation.

If water companies wish to initiate contact to discuss the potential for shared projects, they can contact Jeremy direct and he will be able to direct them to the relevant person in the other water company for that particular project. Supply companies, who may wish to discuss the benefit that they can bring to some of these projects, should use the existing channels to contact the relevant Company.

Leakage Innovation Heatmap 


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Best Practice For Trunk Main Flow Monitoring Areas.

Project Status - Project Completed

Category - Asset Management

A significant number of water companies have started using Trunk Main Flow Monitoring Zones (also known as Water Balance Zones) to locate areas with leakage or unaccounted for water on the trunk mains. Data from these zones help direct leakage detection and consumption recovery efforts.
While some companies are at the maturity stage in their use of Trunk Main Flow Monitoring Zones (FMZs) others are just starting on the journey. There is no best practice or standard for the development or use of FMZs. Creating and maintaining a successful FMZ requires a high amount of effort, investment, time and energy. With future industry’s challenge to reduce leakage and UKWIR’s big question on zero leakage by 2050, it is high time a best practice is developed. The document would build on the UKWIR project: 15/WM/08/55 Leakage Upstream of District Meters, where FMZ’s are mentioned, but details on operational management of them is not.
This would result in an industry consistent approach to monitoring trunk main flow and efficient location of train main leaks.


The impact of reductions in leakage levels on reported and detected burst frequencies.

Project Status - Project Completed

The Water Industry has very little knowledge of the impact of reducing leakage levels on the numbers of repairs that need to be carried out each year, nor on the relative proportions of visible and invisible leaks.

Introduction of performance commitments and changes in SIM, with associated rewards and penalties, has increased focus on the customer service aspects of burst and leak repairs, whether it is unwanted contacts, interruptions to supply or associated discolouration contacts. Customer Service impact mitigation costs will add to the operational costs for repair and consequential damage.

Historic leakage strategy has focused on Sustainable Economic Level of Leakage (SELL). Leakage strategy now must consider the customer acceptability aspects of leakage. Most customer views are based on the impacts of visible or reported leaks and the impact of repairs on customer service.

Single company data is insufficient to discern any impact due to leakage level as it is masked by weather and relatively static targets. Pooled company data, combined with planned AMP6 reductions should provide a data set to understand any increases in repair frequency, changes in proportions of visible leaks and the time period for change.


Understand the balance between use, supply pipe leakage, plumbing losses and meter under-registration.

Project Status - Project Completed

This project will use recently developed flow estimation techniques to investigate these factors across a representative sample of household properties within several water companies.  

The data obtained will be used to provide greatly improved estimates of: 

  • Plumbing losses, which are part of consumption
  • Water running into storage at night, also part of consumption
  • Background leakage on underground supply pipes, which is part of the total leakage KPI


Use of smart meters and smart networks for leakage management.

Project Status - Project Completed

Modern technology has made it possible to collect much greater quantities of data, and at higher resolution. Leakage analysis methods and leak detection technology have both made many advances in recent years, but data collection and manipulation processes have hardly changed. The basic principle of measuring minimum night flow into a DMA, and then subtracting estimates of household and non-household night use to give leakage, remains unchanged in the past 30 years.

However the recent growth in smart networks, and particularly the use of smart meters for revenue purposes, could offer many new opportunities for better leakage management. It is essential that these opportunities and benefits are identified now, so that water companies can take them into account when making their choices of which smart technologies to invest in.


Causes of transients in distribution networks.

Project Status - Project Completed

Category - Leakage


The Impact of Pressure Transients on Leakage.

Project Status - Project Commenced


Understanding how the deterioration of cast iron pipes evolves into leakage.

Project Status - Project Commenced


Achieving zero leakage by 2050: Leakage detection by acoustic methods.

Project Status - Project Completed

No Further Information Currently Available.


Active Leakage Control Efficiency.

Project Status - Project Completed

Both Ofwat and the Environment Agency (EA) have said recently that they have some concerns with the current Sustainable Economic Level of Leakage (SELL) process for the setting of leakage targets.  The recent EA guidance on leakage for Water Resource Management Planning (WRMP19) says :

There is increased realisation that SELL may not be the most effective way to plan leakage levels.  WRMP19 will be the final time that a leakage figure is derived from SELL.  We expect water companies to evolve and move away from SELL for WRMP24 and to innovate to reduce leakage beyond the current levels”.

 The Ofwat consultation document on outcomes for PR19 (February 2017) expresses a different view :

“Companies should report their SELL in business plans, explain their assumptions on future improvements in leakage reduction efficiency in the SELL, and explain how its Performance Commitment for leakage is appropriate in relation to SELL”. 

 There is a strong feeling amongst companies that leakage targets should continue to be based on a sound economic analysis.  However, the cost of leakage management relationship for SELL modelling is derived from analysis of the company’s own historical leakage management performance data.  It is therefore a valid criticism of this process that if a company has been historically inefficient, then this inefficiency becomes built into the SELL.


BQ0-A06 Assessing the levels of leakage on new polyethylene networks.

Project Status - Project Commenced

If the UK water industry aspires to achieve zero leakage from its distribution networks, it is clearly essential that all newly laid networks are leak-free when they are laid and remain leak-free throughout their economic lives. However, a major UKWIR study published in 2010 (Report No. 10/WM/08/43 – “Leakage from Polyethylene Pipe Systems”) determined that leakage levels from recently laid PE networks were indeed significant. This report concluded that, although burst rates per unit length for PE pipes were lower than for other pipe materials, there was “no significant reduction in leakage in DMAs with a high proportion of PE pipework”.

If this is still the case today, then clearly the water companies and their contractors need to take urgent action to rectify the situation. However, the data presented in the 2010 UKWIR report is now all at least 15 years old. Some improvements in field procedures, training of operatives, and non-destructive joint testing have been introduced since then. Furthermore, very little of the data collected for the study were from DMAs which comprised 100% PE mains and services, and the report postulated that the persistently high leakage levels may have been due to increased leakage rates on the remaining non-PE parts of the system. In many of the DMAs used which were not within new housing developments, all, or most of the old mains, and in some cases the communication pipes, had been replaced with PE. But generally, the supply pipes had been disturbed but not replaced, probably resulting in increased supply pipe leakage.

Consequently, while much anecdotal evidence remains to suggest that leakage on new networks is still significant, no more recent quantitative evidence has been collected at national level to support this, and even the 2010 report is questionable.


Combination of transient v steady state detection methods.

Project Status - Project Commenced

Category - Leakage

No Further Information Available.


Optimisation of sensor location: "Hydrant dynamics for acoustic leak detection".

Project Status - Project Commenced

Category - Leakage

No Further Information Available.


Impact of Customer-side Leakage Approaches.

Project Status - Project Commenced

Category - Water Mains & Services & Leakage

It is estimated that about 25% of the leakage within a water distribution network is located on a customer's property and occurs within the pipe that is not the responsibility of the Water Companies. However, this is still included in the leakage figures that water companies report to regulators.

The customers can be divided into household and non- household. For household customers, water companies offer a range of solutions from providing free advice to free repairs. There is limited understanding of how these different policies ultimately impact on reported leakage levels and overall cost to the business. For non household customers, water companies don't provide free repair services as a part of their standard customer leakage policy. However, with the opening of retail market, communication with non-household customers has become difficult, slowing down the leak repair and increasing the level of leakage.

Water Companies are also increasingly installing smart metering which identify leaks with very low flowrates. This has challenged the industry to find such small leaks, which are not cost effective to repair, and can be difficult to locate.


Incidence and causes of repeat bursts at old repairs.

Project Status - Project Completed

Distribution Maintenance staff at water companies know well that many leaks and bursts, once excavated, prove to be at the location of a previous repair, and occur as a result of a failure of the old repair. However it is not known how much data is collected on this, and there is no quantitative evidence of the magnitude or significance of this problem at national level. Nor has there been any study of the reasons for the failures, i.e. whether they are due to deterioration of the clamp or other repair materials over time, or whether they are caused by faulty workmanship at the time of the initial repair.

Many companies do record the types of failure within their records of mains and service bursts. However these descriptions are often very brief (e.g. “pin-hole”), and the fact that the failure was at a previous repair may not be recorded. This project will initially assess the availability of suitable data, in collaboration with participating water companies. The UKWIR National Mains Failure Database may also be a valuable source of data.


BQ02-F24- Improving the testing approach to novel lining materials for potable water networks – Phase 1.

Project Status - Project Completed


BQ02-A30 Optimising the Selection of Pipes for Renewal to Reduce Leakage.

Project Status - Project Commenced

Category - Water Mains & Services & Leakage

In the 1990’s and 2000’s, mains renewal programmes were principally driven by the need to improve water quality in pipe networks, under the Section 19 undertakings.  More recently, mains renewals have been targeted more at improving serviceability, specifically burst frequencies and interruptions to supply. The selection of mains for renewal under these programmes was based first on data on water samples and water quality complaints, and later on data on burst frequencies.  As all of these types of data can be allocated to specific pipes, it was relatively simple to target individual pipes for renewal.

Now, with the current focus on reducing leakage levels, leakage has become a major driver for mains renewal, if not the principal driver.  However, leakage is not normally measured at the level of individual pipes, but only at DMA level.  In reality leakage is rarely uniformly distributed across a DMA, but instead some pipes leak more than others within the DMA.  In order to optimise the economics of a mains renewal programme driven by leakage reduction, a method is required to determine which pipes are leaking most in order to target the investment to maximise the benefits.

Currently, as such a method is not generally available, mains are selected on the basis of historical burst numbers, using burst frequency as a surrogate for leakage.  In reality, burst numbers are a poor indicator of leakage levels.


BQ02-D11 Update on non-acoustic leak detection and location.

Project Status - Project Completed

Category - Water Mains & Services & Leakage

In 2016, as part of the strategic research programme for the Leakage Big Question, UKWIR carried out research into non-acoustic methods for leak detection and location. The research concentrated on reviews of academic literature, conference proceedings and interviews with key contacts amongst manufacturers and academia. In addition, 14 water company representatives were surveyed to find out the extent to which identified technologies had been trailed and the outcomes.

The report investigated the following current methods at the time

•gas detection


•continuous monitoring technologies

•active interventions

•visual inspections

•network pressure and flow data processing


•condition assessment

In addition, the report recommended three areas for further research

•Fibre optic trials for new and existing networks

•Making best se of aerial monitoring methods

•Improving the effectiveness of walking the line

The recent work on the leakage innovation heatmap demonstrated that a number of water companies have both trailed and adopted non-acoustic methods. However, there remains significant questions about the effectiveness of these methods and how best to trial and deploy them.

The purpose of this project is to provide an update on the current market solution non-acoustic methods in use and investigate why some roll-outs of these technologies have been successfully and others have struggled. In addition, the project will investigate emerging technologies and their potential for adoption within the water industry.