Water Mains Leak Detection in Gravesend

Symptoms

At a detached bungalow in TN15, moisture was visible on the external wall of the walkway between the house and the converted garage. Inside the converted garage, significant moisture had accumulated beneath the plinth, and the sound of running water could be heard clearly — both signs that a leak had been active long enough to cause meaningful saturation in the area.

On arrival, the engineer noted that the water meter was spinning continuously with no water in use. This is a reliable indicator of an uncontrolled leak somewhere in the supply pipework.

When the internal stopcock was closed, both the meter movement and the sound of running water stopped immediately, confirming the leak was located on the internal pipework after the stopcock.

This type of problem calls for internal leak detection — a systematic process of narrowing down the leak source using non-invasive and targeted investigative methods before any opening up of walls or floors.

Methods Used

The investigation focused on the converted garage, where the moisture and audible water noise had already pointed to the general area. A damp meter was used across the floor to quantify moisture levels and guide the search toward the most affected zone.

Elevated readings were recorded, helping to narrow the leak to a specific corner of the room near the sink unit.

An endoscope camera was then used to inspect the void behind the sink unit without full excavation, and this confirmed water spraying from a fitting in the corner between the sink unit and the wall. With the location established through internal leak detection methods, the sink unit and washing machine were removed and the wall was opened at the identified point to expose the faulty pipework.

Investigation Process

1. 1
   Meter Observed Spinning

   On arrival, the engineer found the water meter spinning continuously with no water in use, confirming an active leak on the supply.

2. 2
   Stopcock Test Performed

   The internal stopcock was closed, causing both the meter movement and the audible running water noise to stop immediately, locating the leak to pipework after the stopcock.

3. 3
   Moisture Readings Taken in Converted Garage

   A damp meter was used across the floor of the converted garage, returning elevated moisture readings that directed the search toward the corner near the sink unit.

4. 4
   Endoscope Inspection Carried Out

   An endoscope camera was used to inspect the void behind the sink unit, revealing water spraying from a 15 mm fitting in the corner between the sink unit and the wall.

5. 5
   Sink Unit and Washing Machine Removed

   With the leak location confirmed, the sink unit and washing machine were disconnected and moved to allow access to the affected wall.

6. 6
   Wall Excavated and Leak Exposed

   The wall was opened at the identified point, exposing the leaking 15 mm fitting on the copper pipework.

7. 7
   Repair Carried Out

   The leaking section was repaired using two soldered straight couplings and a press fit elbow.

8. 8
   Pipes Re-tested and Area Reinstated

   All repaired pipes were pressure tested with no further issues found. The sink unit and washing machine were then reinstated.

Result & Outcome

The leak was traced to a 15 mm copper fitting in the corner between the sink unit and the wall inside the converted garage. The endoscope inspection identified water spraying directly from this fitting, allowing the wall to be opened at a single precise point rather than through exploratory excavation across a wider area.

The repair involved two soldered straight couplings and a press fit elbow to replace the leaking section of pipework. Following the repair, all pipes were pressure tested and no further issues were identified. The sink unit and washing machine were reinstated before the engineer left site.

For internal leak detection jobs of this kind, precision in locating the source before opening walls makes a significant difference to the extent of any reinstatement work needed. The converted garage area will require drying out — a dehumidifier is recommended to clear the residual moisture that had built up under the plinth and in the surrounding structure.