What is Non-revenue water (NRW)?
Non-revenue water (NRW) is the difference between the volume of water put into a distribution system and the volume billed to customers. It includes real losses from leaks and bursts, apparent losses from meter inaccuracy, data errors and unauthorized use, and unbilled authorized consumption.
What it is
NRW is defined in the standard water balance developed by the International Water Association and used in the AWWA M36 water audit method. The balance starts with system input volume and divides it into authorized consumption and water losses.
Real losses are physical: water that leaks from mains, service connections and storage. Apparent losses are commercial: water that reaches a customer but is not correctly measured or billed. Unbilled authorized consumption, such as firefighting or flushing, also counts toward NRW. Each component needs a different response.
Who it applies to / where it is used
NRW is a core performance measure for water utilities and municipalities. The same logic applies inside large private networks such as campuses, airports, industrial parks and military bases, where supplied water does not match metered use.
How it is measured / what evidence it needs
NRW is calculated from metered volumes. The more of the network that is metered, the more precisely losses can be located.
- Bulk and production meter volumes into the system
- Billed metered and unmetered consumption
- Estimates of unbilled authorized consumption
- Meter accuracy and data handling error estimates
- Night flow analysis by district metered area
How Aqueduct helps
Aqueduct reads across SCADA, AMI and bulk meters to localize real losses and flag apparent losses. Control stays with SCADA.
- Water balance by zone and district metered area through aQ WaterGuard
- Minimum night flow analysis and burst detection at 60-second refresh
- Meter anomaly detection to separate apparent losses from real losses
- Work routed into the utility's CMMS, with repairs verified at the meter