Water Mains Leak Detection in Biggin Hill

Symptoms

On arrival, the customer and her tenant confirmed the water bill issue. The water meter was visibly spinning, yet no internal dampness could be detected and no water damage was apparent.

This pattern — high meter activity with no internal trace — is a common starting point for water mains leak detection, pointing strongly toward a loss somewhere in the supply pipe between the meter and the internal stopcock.

Methods Used

A pressure test was carried out on the pipework between the internal stopcock and the meter, and tracer gas was introduced to the same section. Pressure dropped consistently during testing, and tracer gas readings led the engineer to the garage, where a chamber containing a stopcock sits beneath a concrete floor.

Excavation confirmed a heavily leaking tap. After that repair, the meter was still moving — more slowly, but still active — prompting further investigation.

Block paving outside was excavated and checked with an endoscope camera, finding nothing. A second tracer gas test then detected gas escaping from the water meter chamber itself in the footpath.

Water mains leak detection at this property therefore identified two distinct problem points on the same supply line.

Investigation Process

1. 1
   Initial assessment

   The customer and tenant described elevated water bills. The meter was observed spinning with no water in use and no internal damage visible anywhere in the property.

2. 2
   Internal sources ruled out

   A damp meter survey across the property returned no elevated readings. No visual signs of leakage were found internally.

3. 3
   Stopcock isolation tests

   Closing the internal stopcock made no difference to the spinning meter. The external stopcock at the meter was then isolated, though it could not be fully closed.

4. 4
   Pressure and tracer gas test — supply pipe section

   A pressure test was carried out on the pipe between the internal stopcock and the meter. Pressure dropped steadily, and tracer gas was introduced to identify the leak point.

5. 5
   Leak detected in garage chamber

   Tracer gas readings concentrated in the garage, where a subsurface chamber houses a stopcock. The engineer excavated the concrete floor to access the area.

6. 6
   First repair completed

   The leaking stopcock was found to be pouring water. It was cut out and replaced using a universal transition coupling and a 25mm fitting.

7. 7
   Meter still moving after repair

   Re-testing after the repair showed the meter was still active, though moving more slowly than before, indicating a second leak elsewhere.

8. 8
   Block paving excavated and checked

   Block paving outside was lifted and the endoscope camera was used to inspect the surrounding area. No defects or water movement were found.

9. 9
   Second tracer gas test — meter chamber

   A further tracer gas test detected gas escaping from the water meter chamber in the footpath, indicating a leak at or near the meter connection itself.

Result & Outcome

The garage excavation can now be reinstated and re-concreted. The recommendation is for the water meter to be replaced by the relevant authority, which will also resolve the unusable stopcock. Once that work is completed, the supply line should be fully sound.