Non-Revenue Water Reduction in Australia and NZ

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Non-Revenue Water (NRW) is a pressing issue that affects water utilities across the globe, including Australia and New Zealand. With increasing water scarcity and a growing demand for efficient water loss management, engineers and utilities must understand the importance of NRW reduction. This blog post aims to educate engineers in Australia and New Zealand on Non-Revenue Water, how to calculate it using the International Water Association (IWA) Water Balance, and the benefits of reducing NRW for utilities.

What is Non-Revenue Water?

Non-Revenue Water is the difference between the total volume of water produced by a utility and the amount billed to customers. NRW consists of three main components:

  1. Physical losses: These are leaks in the distribution system, including burst pipes and overflowing reservoirs. This can also be called Real Losses.
  2. Commercial losses: These occur due to issues in the billing process, such as metering inaccuracies and unauthorized consumption. This can also be referred to as Apparent Losses.
  3. Unbilled authorised consumption: This includes water used for firefighting, flushing of mains, and other legitimate purposes that are not billed to customers.

Understanding the IWA Water Balance

The IWA Water Balance is a standardised methodology that helps utilities to quantify and and analyse NRW. The balance comprises the following components:

  1. System Input Volume: The total volume of water entering the distribution system.
  2. Authorised Consumption: The sum of billed and unbilled authorised consumption.
  3. Water Losses: The difference between the System Input Volume and Authorised Consumtpion, which represents the total volume of NRW.
  4. Apparent Losses: These are commercial losses and include metering inaccuracies and unauthorised consumption (sometimes called theft).
  5. Real Losses: These are physical losses of water throughout the system, such as leaks and bursts in the water supply network.

Calculating Your Non-Revenue Water

To calculate NRW using the IWA Water Balance, follow these steps:
  1. Determine the System Input Volume (SIV).
  2. Calculate the Authorised Consumption (AC) by adding billed and unbilled authorised consumption.
  3. Subtract AC from SIV to obtain Water Losses (WL).
  4. Calculate Apparent Losses (AL) by estimating metering inaccuracies and unauthorised consumption.
  5. Subtract AL from WL to determine Real Losses (RL).
NRW = SIV – AC = AL + RL
NRW = SIV – AC = AL + RL

Benefits of Reducing Non-Revenue Water

Reducing NRW offers numerous benefits for utilities in Australia and New Zealand, including:

  1. Financial savings: Decreasing water losses leads to lower production costs, resulting in increased revenue for utilities.
  2. Enhanced customer satisfaction: Efficient water management and accurate billing improve customer trust and satisfaction.
  3. Environmental benefits: Reducing water loss conserves resources and minimises the environmental impact of water production and distribution.
  4. Infrastructure optimisation: Proactively addressing NRW helps utilities to identify and prioritise maintenance needs, leading to improved infrastructure management.

Embarking on NRW Reduction

Engineers and utilities in Australia and New Zealand can embark on reducing NRW by:

  1. Adopting the IWA Water Balance methodology to quantify and analyse water losses accurately.
  2. Implementing a comprehensive NRW reduction strategy that addresses all aspects of water loss, including leakage management, pressure control, and metering accuracy.
  3. Regularly monitoring and evaluating NRW reduction initiatives to ensure continuous improvement.


Reducing Non-Revenue Water is a vital step in ensuring the sustainability and efficiency of water utilities in Australia and New Zealand. By understanding the concept of NRW, calculating it using the IWA Water Balance methodology, and implementing targeted reduction strategies, engineers can contribute significantly to water resource management, cost savings, infrastructure longevity, and environmental stewardship in our region. 

As water scarcity and climate change continue to present challenges, it’s more important than ever for engineers to take proactive steps in addressing Non-Revenue Water and securing a sustainable water future for our communities. When coupled with active leak detection, smart water software and other initiatives, the value created is considerable and serious inroads into leakage reduction can be achieved. 

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