Non-revenue water (NRW), or water produced and lost by utilities, is a major concern for water utilities around the world. With an annual cost of $14 billion to U.S. utilities alone, according to a recent report, utilities are seeking solutions to better monitor and manage their water resources.
NRW includes real loss due to leaks in distribution systems or reservoirs, as well as apparent losses resulting from faulty metering, fraud, or unpaid bills. Water utilities around the world report NRW losses, which can be calculated by subtracting the volume consumed by their customers from the volume of water supplied or produce. The average U.S. water utility reports losing 30 percent of its produced water through a combination of real and apparent losses.
Reporting water loss is only half the battle. In the past two decades, the International Water Association (IWA) and other organizations like the American Water Works Association (AWWA) have played a key role in developing a standard methodology for reporting water loss. This standard reporting methodology has helped shift utilities’ mindset to consider not only volume losses, but also the total revenue losses (accounting for the costs of labor, chemicals, and energy usage that go into every gallon of produced water) and how these losses are detrimental to the utility.
Water audits, typically conducted over the course of a year, help accurately monitor water losses and revenue losses by taking into consideration site-specific monitoring and analysis of multiple components (unbilled authorized consumption, apparent losses due to water theft and metering inaccuracies, and real losses from transmission mains, storage facilities, distribution mains or service connections) of the water infrastructure and data management systems to get a comprehensive picture.
One methodology that has been adopted to evaluate water losses in water distribution systems is the District Water Audit (DWA) Method for NRW Component Analysis in District Metered Areas (DMAs). This bottoms -up approach is founded on the creation of DMAs and breaking service areas into districts or zones and establishing a field monitoring and control system in each district to more effectively detect leaks and minimize system losses. Simultaneously, operational adjustments are made in order to synchronize meter reading and billing cycles.
The primary goal of the DWA is to get accurate quantities of:
- Water produced and supplied to customers,
- Actual customer consumption volumes,
- Customer meter inaccuracies within the DMA,
- Water billing structure for customers inside the DMA,
- Water production costs, and
- Billing and receivable data for the district or sub-districts.