Non-revenue water

Non-revenue water is water that a utility produces but does not bill. It has three parts. Real losses are physical leaks and bursts on mains and service pipes and overflows from tanks. Apparent losses are water that reaches users but is not measured or billed correctly, through meter under-registration, data errors and unauthorised connections. Unbilled authorised consumption, such as firefighting and flushing mains, makes up the rest.

In many Indian cities, a large share of supplied water does not earn revenue, which raises costs, wastes scarce water and often leaves taps dry. Intermittent supply makes things worse: pipes that repeatedly empty and refill suffer pressure surges, draw in contaminated groundwater through leaks, and make metering inaccurate.

Reducing losses starts with measurement: bulk meters at sources and district metered areas, small zones of the network fed through metered inlets where night flows reveal leakage. Teams then find leaks with acoustic loggers and correlators, repair them quickly, replace old pipes and service connections, manage pressure with valves, and replace or calibrate customer meters.

Performance is tracked with a standard water balance and indicators such as the percentage of non-revenue water and losses per connection per day. Moving to continuous, pressurised supply with district metering has been shown to reduce losses and improve water quality at the tap.