Forty-two kilometres of main, with the supply never cut

The problem

The network was losing 46 % of the water it produced and there was no intermediate metering: the only reliable figure was the one leaving the works. Without district metering it was impossible to tell whether the loss was leakage, unbilled consumption or a bulk-meter error, so every repair budget was a gamble.

The solution

The network was divided into eighteen district metered areas, each with its own bulk meter and pressure control. With three months of data per district, the loss was located: 61 % of it was concentrated in four sections totalling eleven kilometres.

Rehabilitation went to those sections first, with temporary bypasses that kept the supply running, and the operation afterwards was placed under an availability contract with the loss indicator as the headline metric.

Process

1. 01SectorisationDivision into eighteen districts with bulk meters and isolation valves.
2. 02MeasurementNinety days of continuous minimum night flow logging per district.
3. 03RehabilitationReplacement of the four critical sections with a temporary bypass.
4. 04OperationA five-year contract with a loss indicator and a quarterly review.

Technologies applied

• Electromagnetic bulk metering per district
• Pressure control with pilot-operated reducing valves
• Cellular telemetry with satellite back-up
• Hydraulic model calibrated against real measurement
• Acoustic leak detection on the prioritised sections