Underground Water Mains Leak Detection in Wakefield

Symptoms

At a property in WF1, water was visibly streaming from the wall adjacent to the back patio area. On arrival, the engineer observed this directly — water was clearly escaping at the wall by the patio, confirming the customer's report before any testing had begun.

The customer noted there had been no loss of pressure on the boiler, which provided early context that the issue was unlikely to originate from the heating system. This pointed attention toward the external water mains supply as the probable source of the problem.

A water mains leak detection job of this nature — with visible water egress at an external wall and a concrete patio directly above buried pipework — required a structured approach combining pressure testing, tracer gas, and acoustic methods to confirm the source and pinpoint the exact location before any excavation.

Methods Used

The investigation began with a pressure test of the internal pipework to rule it out as a source. With the internal system holding steady, attention shifted to the external water mains pipework, which failed its pressure test — confirming a leak was present somewhere on the external supply.

Tracer gas was then introduced to the external mains pipe and the patio area was systematically inspected, with gas detected at multiple points across the concrete surface. Acoustic equipment was used alongside this to listen for water movement, which was also detected.

For a water mains leak detection case like this, having corroborating results from both tracer gas and acoustic methods before breaking ground gave a high degree of confidence in the excavation target. A section of the concrete patio was opened up, exposing the pipework and confirming the leak location directly.

Investigation Process

1. 1
   Water streaming observed at wall

   On arrival, the engineer observed water streaming from the wall by the back patio area, consistent with what the customer had reported.

2. 2
   Internal pipework pressure tested

   A pressure test was carried out on the internal pipework at 4.4 bar for 20 minutes. Pressure held at 4.4 bar with no drop, ruling out any internal leak.

3. 3
   External mains pressure test failed

   A pressure test on the external water mains pipework failed, confirming a leak was present on the external supply.

4. 4
   Tracer gas applied to external mains

   Tracer gas was introduced to the external water mains pipe and the patio was inspected. Gas was detected at multiple areas across the concrete surface.

5. 5
   Acoustic equipment used to detect water movement

   Acoustic equipment was used across the patio area and water movement was detected, providing further confirmation of the leak location.

6. 6
   Concrete patio excavated

   A section of the concrete patio was excavated to expose the buried pipework. The leak was found on the lead pipe at the point where it had been filled to cap it off.

7. 7
   Repair completed

   A repair was made using a 25mm MDPE blue plastic pipe, a 20–27mm x 25mm universal coupling, a 25mm end cap, and two 25mm inserts.

Result & Outcome

The leak was located beneath the concrete patio at the external water mains pipe — specifically at a lead pipe where a previous cap-off fill had failed. Excavation exposed the defective section directly, with the location confirmed by both tracer gas detection and acoustic water movement findings prior to breaking ground.

A repair was completed on site using 25mm MDPE blue plastic pipe, a universal coupling, an end cap, and inserts. The use of modern plastic pipework to address a failure on an old lead pipe section is a standard and durable resolution in this type of water mains leak detection scenario.

The customer has been advised to allow one to two weeks for the ground to settle before arranging repair of the concrete patio. The leak source has been eliminated and the supply restored.