Internal Cold Mains Leak Detection in Northampton

Symptoms

The property in NN16 is a bungalow where the water company had confirmed a loss of approximately 3 litres per hour. Despite several visits from other companies, the source of the leak had not been found, though a previous contractor had established that the leak was internal rather than on the external supply.

The customer was left with an unresolved loss and no clear path to a repair.

With the property served by a combi boiler and system pressure holding steady, there were no obvious visible signs to guide the investigation. Internal leak detection was needed to pinpoint the exact location without unnecessary disruption to the property.

Methods Used

A visual inspection of the property was carried out first, during which a faint hissing noise was identified in the bathroom and traced to the area beneath the floor under the basin. A pressure test was then performed, confirming a drop on the hot feed and narrowing the search to that zone.

Acoustic listening equipment and a damp meter were deployed to confirm the precise location of the leak without lifting the floor unnecessarily.

This is the methodical approach that internal leak detection requires — working from audible and pressure indicators down to a confirmed point before any floor tiles are removed. The process avoided unnecessary disruption and allowed the repair to be targeted to a single small area.

Investigation Process

1. 1
   Visual Inspection and Sound Identification

   A visual inspection of the property was carried out. A slight hissing noise was heard in the bathroom and traced to the area beneath the floor under the basin.

2. 2
   Pressure Test

   A pressure test was completed on the system. A small but measurable drop was recorded on the hot feed, confirming an active leak on that circuit.

3. 3
   Acoustic and Damp Meter Survey

   Acoustic listening equipment and a damp meter were used to confirm the leak location beneath the tiled floor under the basin, before any floor coverings were disturbed.

4. 4
   Tile Removal and Inspection

   Two tiles were lifted to expose the area. The concrete was found to have been laid directly over plastic pipework with no protective sleeving or ducting in place.

5. 5
   Fault Identified

   A push-fit coupling was found to be leaking and was barely attached to the pipe. This was the source of the confirmed water loss.

6. 6
   Repair Carried Out

   The damaged section of pipe was removed and replaced with a new piece of 22mm copper pipe, fitted securely to resolve the fault.

7. 7
   Retest and Sign-Off

   The system was pressure tested again following the repair and held successfully. The basin was refitted before leaving the property.

Result & Outcome

The leak was confirmed beneath the bathroom floor under the basin, originating from a push-fit coupling that was barely attached to the plastic pipework. Two tiles were removed to access the fault — no wider disruption to the property was required. The damaged section was cut out and replaced with a new piece of 22mm copper pipe, and a follow-up pressure test confirmed the repair was sound.

For a property in NN16 where multiple previous visits had failed to resolve the issue, this internal leak detection result gave the customer a clear answer and a completed repair in a single visit. The basin was refitted before the engineer left.

One concern remains: the plastic pipework and fittings beneath the bathroom floor have been screeded over without any protective sleeving. This creates a risk of further leaks in the same area over time. Rerouting the pipework from the loft space is strongly recommended to avoid a repeat of the same problem.