Internal Cold Mains Leak Detection in Hessle

Symptoms

With the source isolated to the internal cold water system, internal leak detection was required to establish exactly where the loss was occurring. Given the size of the property and the fact that pipework runs beneath concrete floors, pinpointing the fault without specialist equipment would not have been practical.

Methods Used

Tracer gas detection was carried out across the ground floor, focusing on the areas most likely to be served by the tested pipework. This approach is standard practice in internal leak detection when the pipe runs beneath a solid concrete floor and there is no visible surface sign of where the water is escaping.

The gas was detected in the utility room, under the kitchen unit next to the washing machine, directing excavation to a precise location.

Investigation Process

1. 1
   Meter Behaviour Assessed

   The water meter was observed spinning slowly with no water in use. Closing the internal cold water stopcock stopped the meter completely, isolating the leak to the internal cold water system.

2. 2
   Pressure Test Carried Out

   Working from the kitchen cupboard, the internal cold water pipework was pressurised to 4 bar using an air compressor and held for 30 minutes. The test failed, confirming a leak on the internal system.

3. 3
   Tracer Gas Introduced

   Tracer gas was used to pressurise the same pipework to 4 bar for 30 minutes. Gas was detected in the utility room beneath the kitchen unit next to the washing machine, identifying the precise leak location.

4. 4
   Kitchen Unit Removed and Floor Excavated

   With the owner's agreement, the kitchen unit was removed and the concrete floor dug up at the identified location. A faulty plastic push-fit elbow fitting was found, with the pipework leaking very badly.

5. 5
   Repair Completed and Retested

   The faulty elbow and the affected sections of pipe were replaced. The repaired pipework was pressure tested to 5 bar for 60 minutes with no pressure loss recorded and no tracer gas detected, confirming a successful repair.

6. 6
   Recommendations Made

   The engineer advised that the exposed area be left to dry before the concrete is reinstated, and recommended installing a pressure reduction valve on the internal cold water pipe.

Result & Outcome

The engineer recommended that the broken-out concrete area be left to dry fully before reinstatement, and advised fitting a pressure reduction valve on the internal cold water pipework to reduce stress on the fittings going forward.