Internal Cold Mains Leak Detection in Hertford

Symptoms

The property had underfloor heating running throughout the downstairs, with hot, cold, and heating system pipework all running beneath floor level. A hot water cylinder was located in an upstairs cupboard, and the internal stopcock was in a separate boiler room outside the main building.

The combination of multiple buried pipework systems and the extent of the visible water damage made it essential to isolate each system methodically before identifying the source.

Methods Used

The hot water and recirculation pipework was isolated at the cylinder and pressure tested — the test passed. The softened cold feed was pressure tested separately — that also passed.

The hard water supply, coming directly from the street, failed its pressure test, confirming it as the leaking system. Tracer gas was then introduced into the hard water pipework to confirm the leak zone as the kitchen area, and acoustic equipment was used to pinpoint the location to directly in front of the kitchen sink unit.

Because the units were too large to get the acoustic equipment beneath them, the bottom board of the adjacent unit was cut away to expose the concrete and identify the pipework route before the floor was opened.

Investigation Process

1. 1
   Visual Inspection on Arrival

   The engineer carried out a visual inspection of the property. Massive water damage was found on the skirting in the kitchen next to the fridge, a leak noise was audible from the sink unit, and water was visible between floor tiles.

2. 2
   Damp Meter Survey

   A damp meter investigation was carried out across the kitchen and guest toilet area. Very high readings were identified throughout, consistent with significant water presence beneath the celotex insulation of the underfloor heating.

3. 3
   Hot Water and Recirculation Isolated and Tested

   The hot water and hot water recirculation pipework was isolated at the cylinder. With these isolated, the leak noise was still audible, and a pressure test on this circuit passed — confirming no leak on the hot water system.

4. 4
   Softened Cold Feed Pressure Tested

   The internal cold feed pipework, supplied via the water softener, was pressure tested. The test passed, eliminating this circuit from the investigation.

5. 5
   Hard Water Supply Pressure Test Failed

   The hard water supply — the drinking water line coming directly from the street — was pressure tested. The test failed, confirming a leak on this pipework circuit.

6. 6
   Tracer Gas Investigation

   Tracer gas was introduced into the hard water system. The detector identified the kitchen area as the location of the leak, focusing the investigation.

7. 7
   Acoustic Equipment Deployed

   Acoustic equipment was used to narrow down the leak location within the kitchen. The equipment pinpointed the leak to directly in front of the kitchen sink unit.

8. 8
   Floor Opened to Expose Pipework

   Because the kitchen units were too large to position the acoustic equipment beneath them, the bottom board of the adjacent unit was cut away to expose the concrete and clarify the pipework route. The tiling and concrete floor in front of the sink unit were then opened.

9. 9
   Leak Identified and Repaired

   A single large leak was found on a section of 15mm copper pipework serving the fridge freezer. The leaking section was replaced with new copper pipework, which was then lagged to protect it.

10. 10
    Hard Water System Retested

    A pressure retest was carried out on the hard water cold feed pipework. The test passed, confirming no further leaks on the system.

11. 11
    Boiler Room — Automatic Air Vents Replaced

    The customer had also reported the heating system losing a little pressure weekly. A leaking automatic air vent was identified in the boiler room; both automatic air vents were replaced and isolation valves fitted beneath them.

12. 12
    Outside Tap Valve Replaced

    A 15mm lever ball valve on the outside tap pipework was found to be slowly but constantly dripping and was replaced. Water pressure was restored to working order throughout and the site was cleaned up.

Result & Outcome

The internal leak detection process identified a single large leak on a section of 15mm copper pipework beneath the kitchen floor, directly in front of the sink unit. The leaking section was on the hard water drinking supply line running to the fridge freezer. The failed pressure test on the hard water circuit, confirmed by tracer gas and pinpointed by acoustic equipment, gave a precise location that allowed the floor to be opened in a targeted area rather than speculatively.