Internal Underground Mains Leak Detection in Guisborough

Symptoms

The owner of a property in YO18 had been notified by their water supplier of a suspected leak on the water supply. On arrival, the customer also reported an unusual noise coming from the pipework in the kitchen — a common secondary indicator that something was wrong beneath the surface.

The combination of a water supplier alert and audible pipe noise pointed toward a pressurised leak somewhere on the incoming mains supply. In cases like this, the source is rarely visible without investigation — pipes running under floors and through walls can leak silently for some time before any obvious surface signs appear.

Water mains leak detection requires a structured approach to narrow down the location before any excavation is considered.

With the leak unconfirmed and its precise location unknown, a full survey of the property was carried out using multiple methods to identify exactly where the water was escaping.

Methods Used

Given that the water supplier had flagged a leak and the mains pressure test failed, the investigation focused on tracing the route of the incoming supply through the property. Thermal imaging was carried out across the lounge floor to detect cold anomalies consistent with water movement beneath the surface, followed by moisture readings to check for elevated damp levels in the same area.

Both returned notable results, establishing the lounge as the primary area of concern.

To confirm the exact leak point, tracer gas was introduced to the external water mains pipe — a standard tool in water mains leak detection when the pipe route runs under solid floors. The property was then inspected for gas escape, with detection confirmed in the lounge.

Acoustic equipment was used to identify the precise point of water movement within that zone, giving a clear target location before any excavation took place.

Investigation Process

1. 1
   Customer report noted

   On arrival, the customer described a noise on the kitchen pipework and confirmed the water supplier had notified them of a suspected leak on the supply.

2. 2
   Pressure test carried out

   A pressure test was applied to the water mains supply, which failed, confirming an active leak somewhere on the incoming line.

3. 3
   Thermal imaging of lounge floor

   A thermal CCTV survey was carried out across the lounge floor and identified cold anomalies consistent with water beneath the surface.

4. 4
   Moisture readings taken

   A damp meter was used to take readings across the lounge floor, detecting relatively high moisture levels throughout the area.

5. 5
   Tracer gas test conducted

   Tracer gas was introduced to the external water mains pipe and the property was inspected; gas was detected in the lounge, confirming the leak location.

6. 6
   Acoustic survey performed

   Acoustic equipment was used in the lounge to detect the sound of water movement, identifying the precise point for excavation.

7. 7
   Floor excavated and leak exposed

   With the customer's permission, the lounge floor and ground were excavated to expose the leaking pipework.

8. 8
   Repair completed

   Once the leak was exposed, a repair was carried out using 25mm Philmac equal couplers, inserts, and a section of 25mm blue MDPE plastic pipe.

Result & Outcome

Excavation of the lounge floor exposed the leaking section of the water mains supply pipe running beneath it. The repair was completed on site using two 25mm Philmac equal couplers, four 25mm inserts, and a replacement section of 25mm blue MDPE plastic pipe — the standard materials for a durable underground mains repair.

The precision of the result was made possible by running multiple detection methods in sequence. For a water mains leak detection case where the pipe runs under a solid floor with no visible surface break, the combination of failed pressure test, thermal anomalies, elevated moisture, tracer gas detection, and acoustic confirmation left no ambiguity about where to dig.

To address the underlying cause, a full replacement of the main water supply line is recommended. The incoming pressure currently exceeds what the existing pipework can safely handle, presenting an ongoing burst risk. The recommended reroute — connecting the new line via the downstairs bathroom plumbing and capping the original entry point — offers a more efficient solution than a like-for-like replacement. Damage to the lounge floor from the excavation will also need to be made good as part of the reinstatement works.