Internal Cold Mains Leak Detection in Ingleby Greenhow

Symptoms

At a property in TS9, water was penetrating the rear wall and elevated water bills had flagged a pattern of high consumption. A local plumber had already investigated the source of the leak at the back of the property without success, leaving the cause unresolved.

Water damage was also visible on new plasterwork around the internal stopcock, suggesting the problem was somewhere within the internal supply pipework.

The water meter at the front of the property was showing continuous usage, and the internal riser — located at the back of the property adjacent to the kitchen — was identified as the relevant section of the supply to investigate. This combination of ongoing meter movement, visible water damage, and a failed prior investigation made this a clear case for internal leak detection, requiring specialist equipment to pinpoint the source.

Methods Used

The investigation began at the water meter, where flow monitoring confirmed uncontrolled usage at a rate of one litre per ninety seconds. Isolating the internal stopcock stopped all recorded usage, immediately directing attention to the internal supply pipework.

Acoustic profiling was then used to narrow the area of concern to the section of pipe running between the internal stopcock and the cold water feed to the kitchen sink.

To refine the location further, tracer gas was introduced into the pipework and a full sweep of the property was conducted with a gas analyser. Elevated readings beneath a kitchen unit adjacent to the sink confirmed the leak position.

With the customer's agreement, the unit and floor screed were lifted, exposing a corroded 15mm copper pipe — the source of the leak. This sequence of staged, evidence-led steps is what internal leak detection is designed to deliver: a confirmed location before any unnecessary opening up of the property.

Investigation Process

1. 1
   Meter flow confirmed

   The water meter at the front of the property was monitored and showed continuous uncontrolled usage of one litre every ninety seconds, confirming an active leak on the supply.

2. 2
   Internal supply isolated

   The internal stopcock was closed and all meter movement stopped, confirming the leak was within the internal supply pipework rather than the external mains.

3. 3
   Acoustic profiling conducted

   Acoustic correlation was used to profile the pipework and identified an area of concern between the internal stopcock and the cold water feed to the kitchen sink.

4. 4
   Tracer gas introduced

   Tracer gas was introduced into the pipework and a full sweep of the property was carried out with a specialised gas analyser.

5. 5
   Leak location confirmed

   Elevated gas readings were detected beneath a kitchen unit adjacent to the sink, pinpointing the leak position prior to any physical investigation.

6. 6
   Floor screed and unit lifted

   With the customer's agreement, the kitchen unit and floor screed were removed, exposing a 15mm copper pipe showing significant corrosion, consistent with friction against unprotected pipework.

7. 7
   Pipework replaced

   The corroded section was removed and repiped using flexible push-fit pipe and connections, suited to the restrictive pipe layout in that area.

8. 8
   Repair pressure tested

   The repaired section was pressure tested at four bar with tracer gas and showed no loss over the monitoring period, confirming a sound repair. The water meter recorded no further usage.

Result & Outcome

The leak was found beneath a kitchen unit adjacent to the sink, emanating from a 15mm copper pipe that had corroded — most likely as a result of friction against unprotected copper pipework. The exact position had been confirmed by tracer gas before the floor was opened, meaning the excavation was targeted and limited to the affected area only.

The corroded section was removed and replaced with flexible push-fit pipe and connections, which was the appropriate solution given the restrictive pipe layout. A pressure test at four bar confirmed the integrity of the repair, and no further usage was recorded on the water meter, verifying that the leak had been fully resolved.

As a result of this internal leak detection job, the repaired area must remain accessible in accordance with water regulations — fittings should not be re-encased in screed or concrete. A full drying procedure is also recommended for all water-damaged areas, which may require lifting further kitchen flooring to address moisture that has spread beneath the surface.