Underground Water Mains Leak Detection in Gloucester

Symptoms

With the stopcock closed and the sound still audible, the situation indicated a significant loss of water somewhere between the street main and the property. This is a common presentation in water mains leak detection work, where the leak lies underground and out of sight.

A large volume of water was also found sitting inside the property, adding urgency to locating and resolving the source.

Methods Used

Water mains leak detection on external supply pipes requires this combination of pressure testing and tracer gas when the pipe is buried and the leak cannot be seen. Each step on this job built on the last: meter observation confirmed the problem, pressure testing quantified it, and tracer gas with acoustic listening pinpointed it precisely enough to dig in one location.

Investigation Process

1. 1
   Customer reports noise

   The occupants noticed the continuous sound of running water from the bathroom with no appliance or tap in use.

2. 2
   Plumber isolates stopcock

   A plumber attended and isolated the internal stopcock; the noise persisted, indicating the leak was on the external mains supply.

3. 3
   Meter observation on arrival

   The internal stopcock was isolated and the water meter was observed spinning continuously and at high speed, confirming a significant active leak.

4. 4
   Pressure test confirms leak

   A pressure test was carried out on the pipework and confirmed there was a measurable loss, consistent with an active underground leak.

5. 5
   Tracer gas introduced

   Tracer gas was added to the pipework and detection was carried out at the front of the property, returning a strong positive reading.

6. 6
   Acoustic listening confirms location

   Acoustic equipment was used on the pipe at the front of the property, and the leak could be clearly heard, pinpointing the position.

7. 7
   Customer agrees to excavation and repair

   The customer agreed to proceed with digging out the identified location to carry out the repair.

8. 8
   Excavation and leak found

   The ground was dug out and a corroded coupling — previously buried underground — was found to have completely failed at the identified location.

9. 9
   Repair completed and re-tested

   The failed coupling and surrounding pipe were removed and replaced with new fittings and copper pipe; a pressure test confirmed no further leaks on the external mains.

10. 10
    Customer witnesses findings

    The customer was present throughout the excavation and repair and witnessed the corroded coupling and the completed work.

Result & Outcome

Excavation at the front of the property revealed a coupling that had been installed underground and had completely corroded away, causing the continuous loss of water. The corroded coupling and the affected section of pipe were removed. Two new 20 mil couplings, reducing kits to 15 mil copper, and new copper pipe were installed to complete the repair. A pressure test carried out after the repair confirmed there were no further leaks on the external mains.