Leakage

Ref: 22/WM/04/14            Price: £10

ISBN: 978-1-84057-950-5

Pressure transients contribute to water company assets’ degradation and structural failure, leading to, amongst other things, leakage and pipe bursts. In recent years, several water companies have undertaken programmes of varying size to capture high frequency pressure data, providing valuable information about the extent of pressure transients across the distribution networks. 
However, many such programmes have, justifiably, been driven by the operational needs of the individual water companies and therefore focused on specific network areas/issues. As such, certain network areas, such as non-pumped zones, that are not traditionally associated with having pressure transients, may have been excluded. As an industry, we still do not have a clear picture of the overall frequency and severity of pressure transient with various causes.

This project analyses the distribution and characteristics of pressure transient events. The analysis suggests that, across the whole UK water network, an event occurs once every 1.4 hours, approximately 6,500 events a year. Each one of these events has the potential to cause failure of the water main either by catastrophic failure or increases in leakage.

Most transients are relatively small in size, with a median amplitude of 12.9m/hd. They typically last around 60 seconds. Approximately, 1.2% of transients drop to atmospheric pressure or below, which could cause ingress and water quality concerns. From the analysis, for approximately 60% of transient events, there was a change in pressure from before to after the transient was observed. These changes are most likely associated with a pumping activity, or as the result of a pressure controlling valve. Although the costs and benefits of addressing the root causes of transients will vary from situation to situation, the findings of this report can assist companies in making their own cost benefit analysis.

This study provides an overview of occurrence and severity of pressure transients across the industry. However, it also highlights a lack of the availability, accessibility, and quality of critical data to enable detailed investigations on the impact of the transient on asset failure. Further studies are recommended to understand the characteristics of transients including the variability of pressure changes in the network, transient shape and unique signature, and categorisations of events and root causes. A recommended approach to future logging programmes is laid out so that water companies can get maximum benefit from the data that is collected.

Ref: 20/WM/08/74 -(1)            Price: £10

ISBN: 

Please note - this publication is an interactive PDF, provided on a CD - no printed report is provided.

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 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 has been no best practice or standard for the development or use of FMZs to date. 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, a best practice guide for FMZs is needed and gaps in the knowledge and technology for managing trunk mains should be identified.

This interactive pdf provides a quick and easy guide to establishing the approach and the factors which should be considered. It is an overview and anyone who requires more detail should consult the full report (20/WM/08/74).

Ref: 20/WM/08/74            Price: £10

ISBN: 978-1-84057-910-9

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 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 has been no best practice or standard for the development or use of FMZs to date. 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, a best practice guide for FMZs is needed and gaps in the knowledge and technology for managing trunk mains should be identified.

The document builds 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 and provides a detailed review of the approach as well as detailed guidance on how to establish them.

Ref: 19/WM/08/70            Price: £10

ISBN: 978-1-84057-880-5

The purpose of this UKWIR project was to gather information to identify and review the use of smart metering and smart networks for leakage management. To review the status of the water industry in the UK and Ireland and internationally both currently and looking towards the future with regards to how smart meters and smart networks can assist in improving and developing better leakage management. The project produced:

1) A report covering the detail of the current practices, looking forward to emerging solutions, identifying areas of opportunity for better leakage management, the benefits of smart networks and recommendations for UK and Irish water companies.

2) A technology scan reviewing smart metering and smart network products. The technology scan looked at both existing products that have had significant use by the industry and new emerging solutions some of which have the potential to transform the way water companies use smart networks for leakage management.

Ref: 19/WM/08/71            Price: £10

ISBN: 978-1-84057-883-6

Analysis was undertaken at a national level to examine the proportion of mains bursts that are caused by failures of previous repairs, and how these vary between pipe materials and UK water companies.

Bursts identified as such were analysed to determine the likely cause of the failure; whether this was due to issues present at the time of the initial repair (e.g. poor workmanship), or to deterioration of the repair materials used.

Focusing on issues identified in the analysis, consolidated guidance has been prepared for maintenance operatives carrying out mains repairs in order to minimise the risk of future repeat failure.

Ref: 18/WM/08/67            Price: £10

ISBN: 1 84057 863 7

A burst-driven renewal programme can achieve a reduction in burst frequencies leading to a reduction in the natural rate of rise (NRR) of leakage. This results in a reduction in the optimal survey frequencies, in turn reducing the costs of active leakage control (ALC) to maintain leakage at the current level. Understanding the full impacts on a range of key performance indicators (KPIs) for a DMA improves will help the industry to take a full totex view of benefits of future investment and allow existing asset management models to be calibrated appropriately.

This study assessed the historic impact of burst-driven mains renewal (mains only) on the operational costs of leakage management on DMA network performance. A representative industry dataset of 487 burst-driven mains renewal schemes from four Water Service Providers (WSPs) was included. Data was normalised to mitigate variation linked to operational, geographic, and climate differences between WSPs. The normalised dataset was used to build non-linear models to predict the performance of KPIs at the level of DMA based on DMA characteristics and current performance.

KPI performance was successfully modelled for each of NRR, total DMA mains repair numbers, mains repairs numbers of renewed sections, leakage, minimum achieved leakage, and supply interruptions.

This report details the new model development and approaches to quantify and optimise the targeting of burst-driven mains renewal programmes by application of individual company data sets. The findings have been incorporated into an Excel tool for ease of application to individual company data sets to support investment planning and optimisation.

Ref: 17/WM/08/59            Price: £10

ISBN: 1 84057 845 9

Three of the key parameters in the analysis of leakage data are Average Zonal Night Pressure (AZNP), Average Zonal Pressure (AZP) and Hour-day factor (HDF).  Previous work has identified a need to review the methodologies for assessing these and provide guidance, with the aim of ensuring that methodologies are applied consistently across the industry.

The project reviewed the methods currently used by UK companies and identified the advantages and disadvantages of each.  It concluded that the appropriate method for a particular company to apply in the present circumstances is dependent on the available data.

The report provides UKWIR members with a standard set of methodologies for assessing these key parameters given the data that is currently available. It also provides a roadmap that can be used to guide improvements to data collection and methodology in the future. Application of the guidance will improve confidence in estimates for both water companies and regulators.

Ref: 17/WM/08/66            Price: £10

ISBN: 1 84057 848 3

An important part of quantifying leakage using DMAs is removing the legitimate night use from the minimum night flow. Over recent years several water companies have been investigating the use of 'fast logging' techniques and their application to estimating night use.

The onjectives of this project were to review the various fast logging systems for estimating night use, demonstrate the effectiveness or performance of the techniques and to provide guidance on how to use and supply the methods.

The report provides guidance on how to use fast logging in small areas and in DMAs. Various factors impact how much of the toal night use can be detected with fast logging, and these are explained in the report. Guidance is also given on how to apply fast logging for consistent regulatory leakage reporting.

Ref: 17/WM/08/65            Price: £10

ISBN: 1 84057 840 8

This project is one of five UKWIR projects that form a strategic research programme to address the question “How can we achieve zero leakage by 2050?”. It covers the subject of water accounting and quantification methods.

The project has considered the current sector knowledge in the UK and overseas relating to the quantification of leakage. A detailed technical review of the area, including each aspect of the ‘top down’ and ‘bottom up’ assessment of leakage estimates and all factors which comprise the reported leakage key performance indicator, has been undertaken.  

You can download this report FOC via the UKWIR website. 

Ref: 17/WM/08/64            Price: £10

ISBN: 1 84057 839 4

This project is one of five UKWIR projects that form a strategic research programme to address the question “How can we achieve zero leakage by 2050?” The project aimed to identify what research and development will be required to facilitate the path to zero leakage.

The objective of this report is to identify the issues (design, materials and workmanship) that currently contribute to high leakage rates and to examine how changes to current installation practices or the need for new techniques are required to facilitate laying leak-free new networks.

You can download this report FOC via the UKWIR website. 

Ref: 17/WM/08/63            Price: £10

ISBN: 1 84057 838 6

This project is one of five UKWIR projects that form a strategic research programme to address the question “How can we achieve zero leakage by 2050?” The project aimed to identify what research and development will be required to facilitate the path to zero leakage.

This report focuses on leak repair techniques and in particular no-dig solutions to water leakage.

You can download this report FOC via the UKWIR website. 

Ref: 17/WM/08/62            Price: £10

ISBN: 1 84057 837 8

This project is one of five UKWIR projects that form a strategic research programme to address the question “How can we achieve zero leakage by 2050?”. The project aimed to identify what research and development will be required to facilitate the path to zero leakage.

This report focuses on non-acoustic methods of leak detection and location. It is complemented by a review of acoustic methods that has been carried out by the Institute of Sound and Vibration Research at the University of Southampton (reported separately).

You can download this report FOC via the UKWIR website. 

Ref: 17/WM/08/61            Price: £10

ISBN: 1 84057 836 X

The work described in this report was undertaken under the UKWIR zero leakage 2050 programme. This report addresses Lot 2, Leak Detection and Location Methods, and focuses on addressing issues related to this area of work. In particular, research related to detection and location methods which exploit acoustics and/or vibration in some form is addressed. This includes, for example, correlation methods, acoustic emission methods and optical fibre sensing methods; thus the work extends beyond those methods which are traditionally thought to be “acoustic”. The work focuses on both potential enhancements to existing technologies and possibilities for novel techniques.

You can download this report FOC via the UKWIR website. 

Ref: 17/WM/08/60            Price: £10

ISBN: 1 84057 835 1

This project is one of five UKWIR projects that form a strategic research programme to address the question “How can we achieve zero leakage by 2050?”. This project covers the subject of the basic mechanisms that control bursts and leakage; these typically stem from the materials that are used in the various UK water networks and the manner in which they degrade over time.

You can download this report free of charge

Ref: 15/WM/08/57            Price: £10

ISBN: 1 84057 794 0

The project reviewed current practice and methods together with company views on their practicality and unintended consequences.

The project has resulted in the development of an expectation model for the find rate of leakage detection technicians. This provides the basis to take into account two primary explanatory factors in interpreting the data between different groups of technicians and between utilities and hence provides a basis to benchmark their performance.

The project has been unique in that it has included a pilot where a given DMA has been surveyed by different technicians immediately following each other. This has provided a significant insight into the leakage detection process, its difficulties and issues.

The pilot has given an initial indication of possible incentivisation techniques, their issues and benefits. This could provide the basis for more extensive trials within utilities.

Ref: 15/WM/08/56            Price: £10

ISBN: 184057 763 0

This project has provided a methodology for assessing the most economic process for management of customer-side leakage, allowing the options for customer side leakage management to be considered alongside all other leakage management options in SELL models.

The economic policy is the least cost mix of repair / replace and the level of company contribution that results in the lowest overall sum of:

- Cost of lost water
- Cost of dealing with customers
- Cost of supply pipe repairs and / or replacements.

There are also a range of issues that can impact on both the level of supply pipe losses and the cost of the SPL policy. The frameworks allow companies to explore the impact of:

- Customer metering
- Separation of shared supplies
- Transfer of ownership.

The supplied MS Excel frameworks(s) and SELL integration module can be used to identify the economic level of supply pipe losses based on company specific information.

Software on CD: MS Excel 2010 & MS Excel Macro-Enabled Worksheet

Ref: 15/WM/08/55            Price: £10

ISBN: 1 84057 751 7

While there has been significant research on leakage within district meter areas, leakage on the part of the network between the distribution input and district meter is less well understood. Water losses from trunk mains and service reservoirs arise from a variety of sources that require different approaches to management. This has led to informal management of upstream leakage and limited development of overall strategy. The extent of data collection to support analysis varies significantly across the industry.

This project has provided a framework for the economic assessment of upstream leakage and identified the advantages and disadvantages of different Active Leakage Control options to managing upstream leakage. Comparison of capital-intensive approaches to management with increased operational expenditure is included, as is incorporation within Sustainable Economic Level of Leakage analysis. Case study applications of the framework have been developed to assist companies in understanding the economic calculations and tailor these to their own circumstances.

Ref: 15/WM/08/54            Price: £10

ISBN: 1 84057 750 9

District meters are essential to leakage management and increasingly used in pressure management and smart networks. Understanding their performance, therefore, is important. Currently the majority of district meters are turbine types but the proportion of electromagnetic meters is increasing. Data from many sources have been analysed to identify the influence of factors, including sizing, installation and age, on installed accuracy. Electronic verification maintains confidence in electromagnetic meters and hydrant meters used to check mechanical meters when problems are suspected. The uncertainties of individual meters should be evaluated when compiling bottom up leakage estimates. However, this process requires good asset records.

Ref: 14/WM/08/53            Price: £10

ISBN: 1 84057 738 X

The project investigated household night use and the factors that influence the night use. The study found that night use varies through the year, and between different geographic regions. However, most companies still apply a single value throughout the year and to all DMAs.

The day-to-day variability (as a proportion of the mean) in night use is much higher than that for daily consumption, whilst the seasonal variation is much lower. The study found that whilst it is extremely difficult to predict the variation in night use, it is possible to monitor the trend in night use through the year using a control group monitor.

Spatially, the study found that household night use can be estimated at DMA level, based on DMA and socio-demographic attributes. A set of normalised factors were developed that can be used to adjust night use across different DMAs in a company.

Ref: 13/WM/08/52            Price: £10

ISBN: 1 84057 705 3

Understanding of the UK supply pipe asset base is limited. Although not owned by the water companies, the supply pipe is a source of leakage.

The report identifies the diverse industry drivers for greater understanding of supply pipe leakage (SPL). Factors such as increasing meter penetration affect SPL estimates significantly.

The current methodology for estimating supply pipe leakage lacks sufficient data in some areas to produce reliable results.

The report provides a specification for additional data collection that will allow improved estimates to be prepared. The data collection approach is independent of the SPL estimation methodology to be applied, allowing further development of the methodology to overcome current issues.

A national initiative is proposed that will enable water companies to collect data in a consistent manner. Following future collection of data, and collation of suitable existing data, improved analysis can be obtained from the pooled data resource.

Ref: 13/WM/08/51            Price: £10

ISBN: 1 84057 697 9

Currently most UK water companies use the minimum night flow method for quantifying and reporting leakage levels. As companies' domestic and commercial meter penetration increases it should be possible to carry out DMA level water balances which will offer an alternative methodology for quantifying leakage. This project researched whether it was possible to build a generic model that would predict a meter penetration level at which the DMA level water balance could be considered more accurate. The project concluded that building such a generic model was not possible. It did, however, produce a model that can be used as a model for a single DMA. This model will determine which water balance, the traditional MNF or the alternative DMA level, would provide a more accurate determination of leakage at the DMA's current level of domestic meter penetration.

The model also indicates, at a company, WRZ or other level, the meter penetration point at which the alternative method would provide a higher proportion of more accurate estimates.

Ref: 13/WM/08/50            Price: £10

ISBN: 1 84057 683 9

Weather conditions have had a severe impact on bursts and leakage in recent years and water companies are seeking relationships to explain and predict this impact for severe weather events. This report explores available weather parameters and proposes models to identify the probability or severity of bursts or leakage exceedance above a threshold. Weather parameters derived fro measurements such as air temperature and soil moisture deficit are used. The influence of source watter temperature is identified; temperate borehole source water shows less reaction to weather extremes than open water or river sources. This effect, other local factors (eg soil type) and data limitations prevent the development of a more universal model. However, the report provides sample models that can be adjusted to accommodate these differences in the absence of specific modelling of the local company area.

Ref: 12/WM/08/48            Price: £10

ISBN: 1 84057 646 4

The project investigated the effect of un-measured and under-registered low flows on night-use allowances in leakage calculations, and on estimates of household per-capita consumption.
The study found that the most significant contribution to un-measured and under-registered flows arises from the existence of continuous low flows. Night-use and per-capita consumption monitors need to be adjusted to compensate for the un-measured and under-registered part of this continuous low flow.
Best estimates of the volume flow rate of 'continuous' low flow have been derived during the study and these can be used to compensate for meter non-registration and meter under-registration. Guidance on how to apply these estimates to household night-use and PCC monitors is provided in the report.
The improved understanding of the effect of un-measured and under-registered low flows on night use, and hence leakage calculations, will help the industry to quantify, target and report leakage more effectively.

Ref: 12/WM/08/47            Price: £10

ISBN: 1 84057 647 2

Conventional leak detection techniques often prove ineffective in locating leaks accurately due to the poor acoustic properties in polyethylene pipe and issues such as highly attenuated leak signals, wave speed estimates, poor signal to noise ratios and the sensitivity of sensors.
The project included numerous controlled field tests to investigate and assess the effectiveness of current leak detection on plastic pipe by reviewing the most appropriate techniques, optimum leak noise correlation methodology and the effective range of existing techniques and also identifying opportunities to support innovation.

Ref: 11/WM/08/46            Price: £10

ISBN: 1 84057 613 8

Cost curves are required in economic level of leakage analysis to relate the total or marginal cost of leakage control to the level of leakage. This report reviews current methods for deriving cost curves and identifies changes that can be made to improve their robustness and accuracy. Issues such as the level of uncertainty, leakage control efficiency and impact of seasonal variations are also considered. The report identifies best practice for elements of current methods where this can be established and challenges current assumptions otherwise. The interactions with, and dependence on, other elements of the ELL calculation are noted: these include policy minimum, natural rate of rise and the cost of repairs. The report also provides direction for further method development aimed at improving cost curve derivation in a manner consistent with operational practice and investment strategy.

Ref: 10/WM/08/42            Price: £10

ISBN: 1 84057 563 8

There are two versions of this report available. This version of the report includes seven reports on Managing Leakage, an executive summary, glossary and list of references.

The full priced version "Managing Leakage 2011 – References Included" also includes 20 original UKWIR reports on CD at a significantly discounted price compared to when buying the reports individually.

The original 'Managing Leakage' was published in 1994 by WRc in co-operation with the Water Services Association and the Water Companies Association. It fast became the definitive reference document for leakage control, not just in the UK but throughout the world, with the methodologies recommended in the document identified as best practice.

Since then, research and practice in leakage management has continued to develop with over thirty reports published by UKWIR alone on the subject and related topics. Although much of the original document is still relevant, more recent research has added to the knowledge in some areas, such as leakage economics, pressure management, asset management and leakage location technology.

Managing Leakage 2011 includes those parts of the original document which are still relevant but also more recent studies and developments with over 100 documents referred to and listed. In order to facilitate the use of the document, it has been produced in an electronic format.

Ref: 10/WM/08/42            Price: £10

ISBN: 1 84057 563 8

There are two versions of this report available. This version of the report includes seven reports on Managing Leakage, an executive summary, glossary and list of references. It also includes electronic versions of over 20 previous UKWIR reports, which are referenced in the document and its Bibliography. Not only does this incur a saving of £1,630 compared to purchasing the reports individually, it also allows for much easier cross referencing of the documents.

The original 'Managing Leakage' was published in 1994 by WRc in co-operation with the Water Services Association and the Water Companies Association. It fast became the definitive reference document for leakage control, not just in the UK but throughout the world, with the methodologies recommended in the document identified as best practice.
Since then, research and practice in leakage management has continued to develop with over thirty reports published by UKWIR alone on the subject and related topics. Although much of the original document is still relevant, more recent research has added to the knowledge in some areas, such as leakage economics, pressure management, asset management and leakage location technology.

Managing Leakage 2011 includes those parts of the original document which are still relevant but also more recent studies and developments with over 100 documents referred to and listed. In order to facilitate the use of the document, it has been produced in an electronic format.

Ref: 11/WM/08/45            Price: £10

ISBN: 1 84057 592 1

The objective of this report is to provide guidance in the application of leak localising and detection techniques to individuals responsible for managing the leak detection process.
Implementing the recommendations should lead to more effective and consistent decision making in both the selection of detection methods and the organisation of leak detection operations.
The report includes a decision-making matrix (as a separate spreadsheet) as a guide to the selection of the most appropriate techniques for pinpointing leaks. The report also includes a set of recommendations about data requirements, target setting and training.
The recommendations are based on information obtained from interviews with leakage managers and leakage technicians in nine companies, and equipment suppliers, along with a review of case studies.

Ref: 11/WM/08/44            Price: £10

ISBN: 1 84057 583 2

Leakage targets in the UK water industry are meant to achieve the leakage level that produces the lowest overall cost for society. However there is inherent uncertainty about what these should be in the medium term (5 years) and even more so in the long term (25 years). This project aimed to assess what leakage level could be achieved in the long term, the actions required, technical constraints, critical factors, uncertainties and costs.
The work was carried out using two models of leakage processes, both calibrated to conditions in a typical UK water undertaking and based on real costs of leakage reduction. Projections were made for a range of strategies (including pressure management, active leakage control and renewal); asset deterioration rates and future operating conditions.
This report will be useful for water resource planning, leakage reduction strategies, leakage economics and to understand the impact of leakage reduction on customer's bills in the long term.

Ref: 10/WM/08/43            Price: £10

ISBN: 1 84057 579 4

Polyethylene is now the preferred material for both new and rehabilitated distribution mains. There has been growing concern, however, surrounding PE pipe joint integrity. This UKWIR project was therefore initiated to quantify the scale of potential leakage problems on existing PE systems and drive improved design and construction methods for installing PE pipe.
As electrofusion joints have been found to be significantly more likely to fail than butt fusion and mechanical joints, this is where the focus of the project has been directed. Analysis of failure data and destructive electrofusion joint test records suggest that 20 percent of electrofusion joints will have a life span considerably less than the 50 year design life.
Recommendations from the project include: making changes to current standards for PE pipe installation; improved data capture, training and licensing of welders, and testing during installation; and the need to overcome issues associated with coiled pipes.

Ref: 09/WM/08/40            Price: £10

ISBN: 1 84057 530 1

 The natural rate of rise (NRR) in leakage relates to the underlying rate at which leakage increases within a system. This report examines the relationship between NRR, calculated using the UKWIR best practice methodology, and a range of network characteristics for 6 Water Service Providers (WSPs). Predictive funtions have been developed which estimate NRR at DMA level in response to variations in key chacteristics. Generic funtions can be applied or calibrated to WSPs to estimate future changes in NRR due to ageing, pressure management, mains renewal, DMA size, and network disruption. Functions can be used for 'gap filling' where calculation of DMA NRR has not been possible, and to integrate ALC, pressure management, and infrastructure renewal within leakage economic modelling. in addition a field study undertaken within 3 WSPs measures flow rates for a range of leak types over a 24 week period to assess the degree to which leaks grow.

Ref: 09/WM/08/39            Price: £10

ISBN: 1 84057 524 7

The failure of large diameter trunk mains, though rare, can be highly disruptive to both Water Company and the general public. Failures can have major consequences in terms of public safety, damage to property and interruptions to supply.
This project brings together knowledge and experience from across the UK to gain insights into the possible causes of failure in trunk mains. It has investigated historic trunk mains failure data from UK water companies and identified deficiencies in data quantity and quality. The project has focussed on pooling data from 13 water companies to support a statistical methodology for predicting trunk main failures. A modelling tool has been developed to support effective capital maintenance planning in the long term.
In addition, an accompanying data protocol has been produced, which, if adopted by the industry, will lead to better understanding and more robust modelling of trunk mains failures in the future.

Ref: 08/WM/08/38            Price: £10

ISBN: 1 84057 512 3

Distribution leakage has long been a focus for the UK water industry but as this element has been successfully reduced over recent years, other elements such as leakage from trunk mains and service reservoirs are assumed to be increasing their relative proportion of water loss. Consequently they are becoming an increasingly important and visible component of the water balance.
This report identifies the range of techniques in use across the UK water industry to quantify, locate and pinpoint leakage from trunk mains and service reservoirs. The report provides guidance on the effectiveness and appropriateness of different practices with respect to estimating and controlling leakage from trunk mains and service reservoirs and aims to provide companies with more information to help them deploy limited resources with more precision and effectiveness.

Ref: 08/WM/08/37             Price: £10

ISBN: 1 84057 472 0

There is an increasing expectation that the district metered area (DMA) will provide a reliable measure of leakage for operational purposes. However, issues with DMAs are becoming increasingly apparent as DMA sizes decrease, leakage reduces and analysis is attempted over shorter time intervals.
To meet these expectations greater understanding is required of the nature of the flow components in a DMA to improve the separation of leakage and night use. The project develops further this understanding and provides an alternative methodology which accounts for the characteristics of predominantly household DMAs while also exploiting the potential in using recording intervals shorter than the 15-minutes conventionally used.
The methodology provides a sound basis for further development to account for more complex DMA configuration and composition (including non-households) beyond those DMAs already accommodated. Implementation in practice requires only minor changes to data loggers and receiving systems.

Ref: 07/WM/08/35            Price: £10

ISBN: 1 84057 460 7

This project has improved the understanding of the range of seasonal variations in leakage around the UK and identified some of the underlying factors and the mechanisms. The study concluded that seasonal variations in leakage are common during the winter and characterised by an increase in leakage and bursts. Analysis and modelling suggests seasonal variations in leakage appear to be a function of the pipe temperature compared to its temperature during installation, variable ground support and movement and the degree of ground saturation. A number of recommendations have been made in the report to enable companies to manage seasonal variations in leakage.

Ref: 06/WM/08/34            Price: £10

ISBN: 1 84057 405 4

This is a collaboration between the water industries of the UK and the Netherlands. It explored the differences in leakage levels and leakage control policies between the two countries and identified a number of physical factors which account for the differences in leakage. Three UK leakage detection teams went to Holland to evaluate UK leak detection techniques in the Dutch networks. The study showed that the 'top-down' leakage analysis method at DMA level is feasible, but only where a majority of the properties are metered. In these DMAs the method could be applied to routinely validate the 'bottom-up method'.

Ref: 05/WM/08/32            Price: £10

ISBN: 1 84057 397 X

A supply pipe leakage estimate is required for regulatory reporting. However, a more detailed understanding of proportion of total leakage that is associated with supply pipes will also improve operational allocation of leakage reduction resources.

A methodology is proposed that is based on the bursts and background estimate (BABE) method modified for service pipes and will allow consistent inter- and intra-company comparisons. The methodology can be applied with only basic levels of available data, but results will become more representative as company-specific data are collected and applied to the analysis.

The proposed approach cannot yet be regarded as definitive best practice as there is only limited data and experience of its application. However the framework provided is sufficient to allow best practice to develop. Approaches to further data collection are detailed and further research is recommended.

Ref: 05/WM/08/33            Price: £10

ISBN: 1 84057 393 7

The natural rate of rise in leakage relates to the underlying rate at which leakage increases within a system. NRR is essential for determining the intensity of active leakage control that is required to maintain leakage at a specific level, and the range of methodologies for assessing leakage/cost relationships outlined in the Tripartite Report all rely on a robust assessment of NRR. As an indicator of asset condition, NRR is also central to mains replacement strategy.
This report examines and compares the theoretical and empirical attributes of the alternative NRR assessment methods, the 'burst frequency' and 'nightline' approaches, and provides a set of procedures which facilitate the derivation of consistent NRR assessments suitable for (i) area-level leakage management budgeting; (ii) targeting mains renewal; (iii) targeting active leakage control resources at DMA-level; and (iv) deriving leakage control cost curves for determining economic levels of leakage.

Ref: 04/WM/08/31            Price: £10

ISBN: 1-84057-325-2

A framework has been developed for processing and analysing cost and effectiveness data for DMA prioritisation and leak detection techniques. Initial guidance on suitable assessment criteria is also presented in the report. The necessity for further data collection and field testing to develop comprehensive guidelines was highlighted in the project.

Ref: 03/WM/08/30            Price: £10

ISBN: 1-84057 283 3

Background leakage is an important concept in leakage economics. This report assesses the methodologies available for investigating background leakage and recommends a best practice. The report also develops the understanding of the factors affecting background leakage and goes some way in explaining the differences between operating areas. The relationship between background leakage and the leakage policy adopted is investigated and a new term 'policy minimum' is suggested which is an assessment of the lowest level of leakage that can be attained for a given policy. Possible drivers which might determine a policy minimum are discussed.

Ref: 02/WM/08/28            Price: £10

ISBN: 1-84057-278-7

Leaks from services pipes account for a significant proportion of unaccounted for water in UK water distribution networks. This report covers various aspects of the subject looking principally at detection and location methods. A comprehensive decision chart has been developed to aid the user in selecting the most likely lowest cost repair solution. A prototype twin wall insertion probe has been developed which enables the precise location of a service pipe leak to be determined. The bulk of the report is dedicated to the experiments conducted using neural networks to attempt to characterise service pipe leaks. The aim was to use the acoustic signals given off by a leaking pipe to determine the location and size of the leak as well as the material from which the pipe was made. Whilst some results are promising there is a considerable way to go before the recognition software would be of any commercial value.

Ref: 03/WM/08/29            Price: £10

ISBN: 1-84057-280-9

This project considers the various methods available of predicting both the short and long term effects of pressure management. The report concludes that there is little practical difference between the methods for the majority of conditions but some have advantages at the extremes and that there is a large variability in pressure-leakage relationships for individual zones. The main recommendation is that a linear pressure-flow relationship can be used in large zones, or where high precision of results is not a priority. There is no evidence of a relationship between pressure and mains repair frequency. Keywords: leakage management, pressure management

Ref: 02/WM/08/27            Price: £10

ISBN: 1-84057-271-X

The implementation of the approach detailed in this report will provide companies with a robust statistical method for the estimation of household night consumption, which takes account of known property attributes for each area of application. An improved approach to night flow analysis has been provided which is consistent with the proposed night consumption modelling approach. Taken together, these two components will provide a statistically sound and unbiased approach to leakage estimation, allowing companies to place greater confidence in reported leakage figures. The use of area-specific household night consumption allowances will improve the targeting of leakage control resources.

Ref: 97/WM/08/10            Price: £10

ISBN: 1 84057 036 9

The first update of 'Managing Leakage', the 1995 water industry report. Economics of leakage methodology, both short and long term is developed in detail. There are case studies on whole- life costing. Seven key areas of UKWIR research are summarised including marginal costs, water balances, social and environmental costs, economics of supply pipe leakage and effects of mains rehabilitation.

Ref: 99/WM/08/26            Price: £10

ISBN: 1 84057 165 9

This study has produced a robust and generalised methodology that can be used by individual companies to more accurately determine legitimate non-household metered use. This should improve the accuracy of regulatory reporting and of leakage monitoring and management. Tests indicated that division of the population into a set of groups on the basis of user- type can produce significant accuracy improvements in assessed allowances. The methodology therefore incorporates a user- type stratification design. Alternative design possibilities are also presented and examined in the report. The estimation approach relates individual meter night- use to average billed volume (ABV), for each user- type.

Ref: 99/WM/08/25            Price: £10

ISBN: 1 84057 162 4

Within the annual water balance, water companies have to estimate unmeasured per capita consumption (PCC) for which various methods are available. The primary project objective was to develop best practice for estimating unmeasured PCC. Other objectives were to identify explanatory factors for regional variation in PCC, to assess the benefits of adopting a per household measure and to undertake a feasibility study for a national micro- component monitor. The report contains detailed descriptions of best practice for estimating unmeasured PCC and guides the reader through the steps for designing or reviewing PCC monitors. Conclusions for the other objectives are also given.

Ref: 99/WM/08/24            Price: £10

ISBN: 1 84057 161 6

This research develops a methodology for incorporating environmental and social costs and benefits into the evaluation of water management options. Approaches to valuing changes in external costs are developed. In addition, the methodology provide an approach to updating historical estimates of cost, taking account of existing interventions aimed at internalising external costs, and allowing for sunk capital. The methodology is illustrated with representative case studies.

Ref: 99/WM/08/23            Price: £10

ISBN: 1 84057 160 8

The manual provides guidance to staff engaged in managing district meter areas (DMAs). It guides the practitioner through the stages of :
1.  setting up and maintaining districts,
2 monitoring leakage,
3 selecting leak detection equipment,
4 directing leak detection staff,
5 pressure management,
6 dealing with problem DMAs,
7 using DMA data for other purposes.
The manual is intended as a guide for staff of varying experience in managing DMAs. It provides references to various techniques, but recognises the very variable circumstances across the water industry.

Ref: 99/WM/08/22            Price: £10

ISBN: 1 84057 159 4

This research examines the theoretical and empirical determinants of the natural rate of rise in leakage (NRR) over time, in order to advance the development of an 'NRR Equation' which can be used to produce reliable estimates of the NRR over a wide variety of different DMA conditions. Once derived from a sound empirical basis, such a specification might not only be utilised to determine optimal DMA intervention and exit times and the unit costs of leakage control, but might also be appropriately calibrated in order to produce a measure for asset condition and deterioration.

Ref: 99/WM/08/21            Price: £10

ISBN: 1 84057 158 6

Existing methods for providing leakage estimates for reporting purposes, using data from continuously monitored areas are reviewed. Analysis concentrated on night use allowances and 15 minutes flow sampling intervals using standard meters and loggers It is recommended that reported leakage is based on a rolling 7 day 20 percentile using the minimum rolling hour each night. The method will give a leakage estimate for each day. Monthly and annual estimates should be based on the average of available data for the relevant period.