The Issues and Challenges of Reducing Non-Revenue Water

Rudolf Frauendorfer, Roland Liemberger

• Publisher: Asian Development Bank
• Year: 2010
• Print ISBN: 9789290920953
• eBook ISBN: 9789290921936
• Topic: Technology & Engineering
• Subtopic: Environmental Management
• Index: Technology & Engineering

Improving the efficiency of water utilities and reducing water losses are becoming top priorities in Asia, with its often-limited water resources and rapidly increasing urban population. This publication provides an up-to-date introduction to the subject matter, highlights the complexity of managing non-revenue water (NRW), offers guidance on NRW assessment, and recommends appropriate performance indicators. It is, to a large extent, based on the work of the Water Loss Specialist Group of the International Water Association in the last decade, and is amply complemented by the authors' practical experiences in Asia and in other countries around the world.

Annex 1: Water Balance Definitions

In the following, all terms used in the water balance are listed in hierarchical order—as one would read the water balance form from left to right. Some of the terms are self-explanatory, but are still listed and briefly explained.¹

•System Input Volume: The volume of treated water input to that part of the water supply system to which the water balance calculation relates. It may come from a utility’s own sources and treatment facilities or from external bulk suppliers. It is important to note that water losses at raw water transmission schemes and losses during the treatment process are not part of the annual water balance calculations. In case the utility has no distribution input meters, or they are not used and the key meters are the raw water input meters, the system input has to be based on the raw water meters but must be adjusted by treatment plant water use. In either case, the measured volume has to be corrected for known systematic bulk meter errors.

•Authorized Consumption: The volume of metered and/or unmetered water taken by registered customers, the water utility, and others who are implicitly or explicitly authorized to do so for residential, commercial, and industrial purposes. This also includes water exported across operational boundaries. Authorized consumption may include items such as firefighting and training, flushing of mains and sewers, street cleaning, watering of municipal gardens, public fountains, frost protection, building water, etc. These may be billed or unbilled, metered, or unmetered.

•Water Losses: The difference between system input and authorized consumption. Water losses can be considered as a total volume for the whole system, or for partial systems such as transmission or distribution schemes, or individual zones. Water losses consist of physical losses and commercial losses.²

•Billed Authorized Consumption: Those components of authorized consumption that are billed and produce revenue (also known as revenue water or billed volume). This is equal to billed metered consumption plus billed unmetered consumption.

•Unbilled Authorized Consumption: Those components of authorized consumption that are legitimate but not billed and therefore do not produce revenue. This is equal to unbilled metered consumption plus unbilled unmetered consumption.

•Commercial Losses: Includes all types of inaccuracies associated with customer metering as well as data handling errors (meter reading and billing), plus unauthorized consumption (theft or illegal use).

•Physical Losses: Leakage and other physical water losses from the pressurized system and the utility’s storage tanks, up to the point of customer use. In metered systems, this is the customer meter. In unmetered situations, this is the first point of use (stop tap/tap) within the property.³

•Billed Metered Consumption: All metered consumption that is billed. This includes all groups of customers, such as domestic, commercial, industrial and institutional, and also includes water transferred across operational boundaries (water exported) that is metered and billed.

•Billed Unmetered Consumption: All billed consumption that is calculated based on estimates or norms but is not metered. This might be a very small component in fully metered systems (for example, billing based on estimates for the period a customer meter is out of order) but can be the key consumption component in systems without universal metering. This component might also include water transferred across operational boundaries (water exported) that is unmetered but billed.

•Unbilled Metered Consumption: Metered consumption that is for any reason unbilled. For example, this might include metered consumption by the utility itself or water provided to institutions free of charge, including water transferred across operational boundaries (water exported) that is metered but unbilled.

•Unbilled Unmetered Consumption: Any kind of authorized consumption that is neither billed nor metered. This component typically includes items such as firefighting, flushing of mains and sewers, street cleaning, frost protection, etc. In a well-run utility, it is a small component that is very often substantially overestimated. Theoretically, this might also include water transferred across operational boundaries (water exported) that is unmetered and unbilled (although this is an unlikely case).

•Unauthorized Consumption: Any unauthorized use of water. This may include illegal water withdrawal from hydrants (for example for construction purposes), illegal connections, bypasses to consumption meters, or meter tampering and under-reading of customer meters because of meter reader corruption.

•Customer Metering Inaccuracies and Data Handling Errors: Apparent water losses (water that is only “apparently” lost but causes a loss in revenues) caused by customer meter inaccuracies and data handling errors in the meter reading and billing system.

•Leakage on Transmission and/or Distribution Mains: Water lost from leaks and breaks on transmission and distribution pipelines. These might either be small leaks that are not visible at the surface (e.g., leaking joints) or large breaks that were reported and repaired but did leak for a certain period before that and contribute therefore to the annual volume of physical losses in a particular year.

•Leakage and Overflows at Utility’s Storage Tanks: Water lost from leaking storage tank structures or overflows of such tanks caused, for example, by operational or technical problems.

•Leakage on Service Connections up to Point of Customer Metering: Water lost from leaks and breaks of service connections from (and including) the tapping point until the point of customer use. In metered systems, this is the customer meter; in unmetered situations, this is the first point of use (stop tap/tap) within the property. Leakage on service connections might sometimes be visible but will predominately be small leaks that do not surface and run for long periods (often years).

•Revenue Water: Often called billed volume, includes those components of authorized consumption that are billed and produce revenue (also known as billed authorized consumption). This is equal to billed metered consumption plus billed unmetered consumption.

•Non-Revenue Water: Those components of system input that are not billed and do not produce revenue. This is equal to unbilled authorized consumption plus physical and commercial losses.

•(Unaccounted-for Water) Because of the widely varying interpretations and definitions of the term “Unaccounted-for Water,” it is strongly recommended that this term no longer be used.

Annex 2: List of Key Publications

Alegre, H., et al. 2006. Performance Indicators for Water Supply Services. IWA Manual of Best Practice. 2nd Edition. IWA Publishing.

American Water Works Association (AWWA) Water Loss Control Committee. 2003. Applying Worldwide Best Management Practices in Water Loss Control. AWWA Journal. August.

Fanner, P., J. Thornton, R. Liemberger, and R. Sturm. 2007. Evaluating Water Loss and Planning Loss Reduction Strategies. AWWA Research Foundation.

———. Leakage Management Technologies. AWWA Research Foundation.

Farley, M. and S. Trow. 2007. Losses in Water Distribution Networks. IWA Publishing.

Farley, M., G. Wyeth, Z. Ghazali, A. Istandar, and S. Singh. 2008. The Manager’s NRW Handbook. USAID.

Kingdom, W., R. Liemberger, and P. Marin. 2006. The Challenge of Reducing Non-Revenue Water (NRW) in Developing Countries – How the Private Sector Can Help: A Look at Performance-Based Service Contracting. WSS Sector Board Discussion Paper #8. World Bank.

Lambert, A. 2001. What do we know about Pressure: Leakage Relationships in Water Distribution Systems? IWA Conference System Approach to Leakage Control and Water Distribution Systems Management. Brno, Czech Republic. May.

———. 2009. Ten years experience in using the UARL formula to calculate Infrastructure Leakage Index. Water Loss 2009 Conference Proceedings. Cape Town. April.

Lambert, A., T.G. Brown, M. Takizawa, and D. Weimer. 1999. A Review of Performance Indicators for Real Losses from Water Supply Systems. AQUA. 48(6).

Lambert, A. and R. McKenzie. 2002. Practical Experience in using the Infrastructure Leakage Index. Paper to IWA Conference on Leakage Management – A Practical Approach. Cyprus. November.

Liemberger, R. 2002. Do You Know How Misleading the Use of Wrong Performance Indicators can be? IWA Specialised Conference, Leakage Management – A Practical Approach. Cyprus. November.

———. 2010. Recommendations for Initial Rapid Non-Revenue Water Assessment. Paper to the IWA Water Loss 2010 Conference. Sao Paulo, Brazil.

Liemberger, R. and R. McKenzie R. 2005. Accuracy Limitations of the ILI: Is It an Appropriate Indicator for Developing Countries? In Conference Proceedings, IWA Leakage 2005 Conference in Halifax. Nova Scotia, Canada.

Seago, C., R. McKenzie, and R. Liemberger. 2005. International Benchmarking of Leakage from Water Reticulation Systems. Paper to Leakage 2005 Conference. Halifax. September.

South African Bureau of Standards Code of Practice: SABS 0306:1999. The management of ...

Table of contents

• Front Cover
• Title Page
• Copyright Page
• Contents
• Tables, Figures, and Boxes
• Abbreviations
• Foreword
• Acknowledgment
• Introduction
• Non-Revenue Water: Definition, Terminology, and Approach
• Non-Revenue Water Estimates for Asia
• Non-Revenue Water Impact on Water Utility Efficiency
• Non-Revenue Water Impact on Customers
• Non-Revenue Water and the Urban Poor
• The Importance of Establishing a Water Balance
• What You Should Know about Physical Losses
• What You Should Know about Leakage Reduction
• What You Should Know about Commercial Losses
• The Need for Appropriate Performance Indicators
• Addressing Community Behavior
• Outsourcing of Non-Revenue Water Management Activities
• The Future
• Annex 1: Water Balance Definitions
• Annex 2: List of Key Publications
• Back Cover