Non-Revenue Water (NRW) can be defined as water that is produced for consumption and lost before it reaches the customer. The amount of NRW is typically represented as a percentage, and is made up of both real and apparent losses, as well as unbilled authorized consumption. Real losses refer to water lost from leaks and water main failures, while apparent losses come from theft and metering inaccuracies. Unbilled authorized consumption comes from water that is provided for public services that is not billed, such as fire hydrants.


Causes of Non-Revenue Water:

  • Physical (or real) losses - Leakage from all parts of the system
    • Poor operations and maintenance
    • Lack of active leakage control
    • Poor quality of underground assets
  • Commercial (or apparent) losses
    • Customer meter under registration
    • Data handling errors
    • Theft of water in various forms (e.g. Illegal Connections)
  • Unbilled authorized consumption
    • Water used by the utility for operational purposes
    • Water used for fighting fires
    • Water provided for free to certain consumer groups

A Global Issue

The World Bank estimates that NRW costs utilities worldwide about US$14 billion annually. By reducing these losses by half in areas with the highest NRW, it is estimated that US$2.9 billion cash would be generated and an additional 90 million people could have access to water.

Utilities that run successful NRW-reduction programs often see an increase in revenue and improved service reliability. These utilities also gain a better understanding of their water system which allows for more effective water management in the long-term.

In terms of reducing NRW, locating leaks on large-diameter transmission mains represents the best opportunity for improvement. Leaks on small-diameter distribution mains are the most common, but the volume of water lost from these leaks represents a much smaller percentage of NRW than leaks on large-diameter pipes. Focusing leak and theft detection on transmission mains is the first step in a NRW-reduction strategy.

General Service Objectives

  1. Integrating a new loss management team into the organization and improving the water loss reduction capacity.
  2. Develop the capacities to cope with future challenges.
  3. Enclose methods for water loss management and technical assistance.
  4. Introduce the technical and administrative losses reasons and put them in a record (archive) to build a database which makes it easier to perform repairs or new formulations.
  5. Establishing work procedure routines for the production, for keeping records of failure/repair statistics.
  6. Hold theoretical training and practical training.

Main Service activities

  1. Establish a regional loss management team.
  2. Identify the most suitable pilot area and its representative features.
  3. Set the geographic information system that describes the pilot area
  4. Carry out a water consumption survey and correlate bills records.
  5. Identify losses and its reasons.
  6. Calculations of revenue- non revenue water.

Terminology of Water Losses

System Input Volume Authorised Consumption Billed Authorised Consumption Consumption (including water) Revenue Water
Billed unmetered consumption
Unbilled Authorised Consumption Unbilled metered consumption Non Revenue Water (NRW)
Unbilled unmetered consumption
Water Losses Apparent Losses Unauthorised consumption
Customer metering inaccuracies
Real Losses Transmission and / or distribution mains
Leackage and overflows at utilitiy's storage tanks
Leakage on service connections up to point