Underground Water Mains Leak Detection in Cricklade

Symptoms

Water mains leak detection was needed to establish whether the leak was on the shared external mains pipework and to pinpoint its exact location. The presence of water in the hallway, combined with the fact that the stop cock had already been replaced, suggested ongoing pressure loss on the supply line.

Without a precise location, any repair risked missing the true source of the problem.

Methods Used

Once the hallway tiles and concrete were lifted, a corroded steel pipe was found leaking below the surface. After an initial repair, the pressure test failed again, revealing three further leak points.

Excavation continued through the hallway and outside until sound, uncorroded pipework was reached. This thorough approach — characteristic of a water mains leak detection job involving deteriorated shared mains — ensured all active leak points were identified before the final repair was made.

Investigation Process

1. 1
   Arrival and initial assessment

   The engineer arrived to find the water board had already replaced the external main stop cock. Water was present in the neighbour's hallway from the shared external mains pipework.

2. 2
   Pressure test carried out

   A pressure test was performed on the external mains pipework. The test failed, confirming an active leak was present on the line.

3. 3
   Acoustic and damp meter survey

   Acoustic detection identified an anomaly at the hallway. The damp meter returned high readings on both the hallway floor and wall, confirming moisture ingress in that area.

4. 4
   Hallway floor exposed

   Hallway tiles and the concrete sub-floor were lifted to access the pipework beneath. A corroded, leaking steel pipe was found below.

5. 5
   Initial repair and retest

   The leaking section was replaced, but the subsequent pressure test failed again, indicating further leak points remained on the pipework.

6. 6
   Three additional leaks found

   Continued investigation identified three more leaks on the pipework. Excavation extended further through the hallway and outside to locate all affected sections.

7. 7
   Full section replaced with MDPE pipe

   Excavation continued until sound, healthy pipework was reached. The entire compromised section was replaced using 25mm MDPE pipe with inserts and UTC couplings.

8. 8
   Final pressure test passed

   On completion of the repair, the pipework was pressure tested at 4 bar for 20 minutes. The test passed, indicating no further leaks at the time of testing.

Result & Outcome

The engineer has noted that the condition of the remaining shared mains pipework is poor and recommends full replacement. No guarantee has been given on the wider pipework. Both properties sharing this supply should be made aware of the recommendation to avoid further disruption.