Internal Cold Mains Leak Detection in Lewes

Symptoms

At a property in BN10, leak evidence had begun rising through the floor of a closet WC. Visible damage was present on walls, woodwork, and flooring across both the closet WC and the adjoining hallway, indicating a subsurface leak that had been active long enough to cause widespread saturation.

Because the damage was spread across two areas with no obvious above-floor source, internal leak detection was required to trace the origin before any repair work could begin. The mains supply had already been isolated prior to arrival, meaning the active leak source needed to be confirmed through methodical testing rather than surface observation alone.

The extent of the damp and structural damage to the flooring and woodwork pointed to a pressurised supply leak rather than a drainage issue, making it necessary to reinstate the mains supply under controlled conditions to confirm the source and location.

Methods Used

The investigation began with a visual inspection and damp meter survey across all affected areas in the closet WC and hallway, establishing the extent and distribution of moisture damage. With maximum damp readings recorded on floors, walls, and woodwork in both spaces, the mains supply was carefully reinstated to allow active observation — water was immediately seen rising through the tiled floor at the junction of the two areas.

Acoustic testing confirmed an irregularity from that same location, and thermal imaging identified a thermal mass consistent with pressurised water pooling around localised heating pipework beneath the floor. This combination of methods, standard practice in internal leak detection, narrowed the source to a specific section of 15mm copper mains supply running beneath the central heating pipework, allowing tiles and screed to be removed with precision.

Investigation Process

1. 1
   Visual inspection on arrival

   The engineer visually inspected all affected areas, identifying leak damage — including staining and deterioration — on walls, woodwork, and flooring in both the closet WC and the hallway.

2. 2
   Damp meter survey

   A damp meter test was carried out throughout both spaces. Maximum readings were recorded on the flooring, walls, and woodwork in the WC and hallway, confirming widespread moisture saturation.

3. 3
   Mains supply reinstated

   The previously isolated mains supply was carefully reinstated. Water was immediately observed rising through the tiled floor at the junction of the hallway and closet WC, identifying the active leak zone.

4. 4
   Acoustic test

   An acoustic test was carried out over the area. An irregularity was detected from the same location where water had been seen rising, consistent with a pressurised pipe failure beneath the floor.

5. 5
   Thermal imaging

   Thermal imaging identified a thermal mass beneath the floor, caused by water from the failed mains supply pooling around localised central heating pipework in that area.

6. 6
   Mains isolated, floor opened

   The mains supply was re-isolated and tiles and screed were removed to gain access. A failed 15mm copper mains supply was discovered running beneath the central heating pipework.

7. 7
   Pipe section renewed

   The failed section of 15mm copper mains supply was renewed, with the replacement routed correctly beneath the central heating pipework.

8. 8
   Completion test and customer advice

   The repair was pressure tested on completion and passed. The customer was advised to contact their insurance company to arrange professional drying and all remedial works under their trace and access policy.

Result & Outcome

The leak was traced to a failed section of 15mm copper mains supply running beneath the central heating pipework at the junction of the closet WC and hallway floor. The combination of acoustic correlation and thermal imaging allowed the precise area to be identified before any floor was lifted, keeping the access opening targeted and limited.

Once exposed, the failed pipe section was renewed and the repair was tested under pressure on completion — all passed. The internal leak detection process confirmed the leak source conclusively, meaning the customer now has a clear, documented record of the cause and location to support an insurance claim.

The customer was advised to send the engineer's report to their insurance company to arrange all remedial works, including professionally drying the affected areas. All works fall within the trace and access element of a standard buildings insurance policy.