Approach — NRW Analytics · nrwanalytics.com is for sale

The framework

The IWA / AWWA standard water balance

Everything starts here. The water balance accounts for every volume entering the system and sorts it into what's billed (revenue water) and everything else (non-revenue water) — then splits the losses into apparent and real. It's the common language regulators, lenders, and operators share, and the starting point of the AWWA M36 audit.

Revenue water76.6%

Unbilled2.4%

Apparent6.0%

Real losses15.0%

Revenue water (billed) Unbilled authorized Apparent losses Real losses Right three bands = Non-Revenue Water (23.4%) · illustrative

NRW = System Input Volume − Billed Authorized Consumption. The art is decomposing that one number — because each component is solved a completely different way. Expand each below:

+Revenue water — billed authorized consumption~76.6%

Metered and unmetered water that is both authorized and billed. This is the utility's paying base — the goal of a loss program is to grow this share of system input without producing more water.

+Unbilled authorized consumption~2.4%

Legitimate use that isn't billed — mains flushing, firefighting, street cleaning, and similar. It's part of NRW but generally small and largely unavoidable; the priority is to estimate it credibly rather than eliminate it.

+Apparent (commercial) losses~6.0%

Water that is consumed but isn't billed correctly. Small in volume yet high in value, because it's priced at the full retail tariff.

Meter under-registrationMeter sizing & ageingData & billing errorsUnauthorized use

+Real (physical) losses~15.0%

Water that physically escapes the network — usually the largest volume, and the focus of most leakage programs. Up to ~90% of leakage never surfaces.

Transmission & main leaksService-line leaks to the meterStorage leakage & overflowReported & unreported bursts

Measuring performance

Indicators that actually compare — beyond "percent NRW"

Both IWA and AWWA discourage percentage NRW as the only metric: it moves with consumption and pressure and flatters or penalizes utilities for the wrong reasons. Analytics-led programs track volumetric and infrastructure-normalized indicators instead.

ILI = CARL ÷ UARL

The Infrastructure Leakage Index is the ratio of Current Annual Real Losses to the Unavoidable Annual Real Losses for your specific network — a function of mains length, connections, and pressure. It's dimensionless, so a small rural system and a dense city can compare real-loss management on equal footing. An ILI near 1.0 is the technical floor; higher values signal room — and an economic case — to act.

Real losses · gal/connection/day

$0M

Apparent loss recoverable / yr

3.8

Infrastructure Leakage Index — illustrative

1–2 excellent2–4 good4–8 fair8+ act

Target ILI is set by the economic level of leakage, not a universal number — it depends on the value of water and the cost of intervention in your system.

The IWA/AWWA methodology, end to end.

The IWA / AWWA standard water balance

NRW composition — where the losses actually sit

Indicators that actually compare — beyond "percent NRW"

See it applied to your data.