Non-revenue water reduction: an engineering work plan

Overview

Establish the reporting period and consistent boundaries for system input and billed authorised consumption before calculating NRW. A single percentage does not separate physical leakage, meter inaccuracies and billing issues. Review source records, meter confidence and data timing before comparing locations or periods.

Develop a work plan spanning water balance, asset mapping, hydraulic review, district metered areas, pressure management and field investigation. DMA boundaries and metering need engineering checks for supply continuity and measurement quality. Night-flow observations require interpretation of legitimate demand and measurement uncertainty.

Link each intervention to accepted baseline evidence, a field record and a follow-up review. Document repairs, meter changes and pressure adjustments so that later comparisons are meaningful. Report assumptions and outstanding data gaps with any estimated improvement. ASUTOS preliminary calculators are planning aids and do not replace a validated water balance or hydraulic assessment.

For the initial water balance, record the volume source, reading period, unit and confidence for each input. Check whether source meters, customer reads and billing periods describe the same system boundary and time window. If they do not, explain the reconciliation method and uncertainty. Avoid presenting a precise loss estimate when the input volumes are incomplete or temporally inconsistent.

A DMA investigation should document boundary valves, supply points, meter positions, pressure zones and any cross-boundary connections. Field checks and hydraulic review must establish how isolation or metering affects service. Compare observations with the accepted model and operating records. Where night-flow data is used, identify the assumptions for legitimate demand and the limitations of instrument accuracy and sampling.

Prioritise follow-up using evidence, service criticality and investigation practicality. Keep an intervention log that records the location, date, method, asset, action and review result. Recalculate the agreed performance measure using a comparable period and boundary. EPA EPANET resources can support hydraulic modelling, but the commercial and apparent-loss portions of an NRW programme also require customer, metering and billing evidence outside the hydraulic model.

Further reading

EPA EPANET

Key considerations

• Define the operating question and asset boundary.
• Record input quality, units, ownership and revision.
• Agree review responsibilities and acceptance criteria.
• Verify project-specific requirements before implementation.

Related solutions

Water Supply & Hydraulic Engineering

Non-Revenue Water & DMA Strategy

Wastewater & Industrial Effluent Treatment

Product capabilities

• Define the operating question and asset boundary.
• Record input quality, units, ownership and revision.
• Agree review responsibilities and acceptance criteria.
• Verify project-specific requirements before implementation.