Define 'non-revenue water' (NRW) and its impact in WUE programs.

• A. Water that is produced but not billed due to leaks, theft, or metering errors; reducing NRW increases efficiency.
• B. Water lost to evaporation
• C. Solar energy used to pump water
• D. Water that is treated but not distributed

Answer: (A)

Non-revenue water is water that has been produced and distributed but is not billed to customers. It includes both physical losses (like leaks and bursts in the distribution system) and commercial losses (such as theft or meter inaccuracies and other billing errors). In water use efficiency programs, NRW is a crucial metric because it shows how much water is effectively being lost or unrecovered in the system, even before considering overall demand.

Focusing on reducing NRW helps improve efficiency in several ways: it increases the amount of water available for legitimate use without needing more production, lowers energy and treatment costs tied to pumping and delivering water, and strengthens revenue and asset management by targeting the underlying causes—leak detection and repair, meter accuracy, and preventing unauthorized use. This is why the best answer identifies NRW as water produced but not billed due to leaks, theft, or metering errors, and notes that reducing NRW boosts efficiency. The other options describe phenomena that are not NRW (evaporation, solar pumping, or water that’s treated but not distributed).