Internal Cold Mains Leak Detection in Holbeach

Symptoms

At a large detached property in PE12, water was coming up from beneath the kitchen island. To limit further damage, the customer had capped off the cold water supply to both the kitchen and the downstairs bathroom, leaving both rooms without cold water until the source of the leak could be found.

The external meter was checked with the pipework capped and all other supplies in use — there was no movement on the meter dial, which confirmed the leak was contained within the isolated section rather than an active running loss at that point. The situation called for internal leak detection to establish exactly where beneath the kitchen floor the pipe had failed.

Because the affected pipe ran below a tiled kitchen floor and concrete screed, there was no visible access to the leak without first knowing where to dig. Removing tiles and breaking out concrete across a wide area unnecessarily was not an option, so a targeted detection approach was required.

Methods Used

The engineer isolated the hot feeds to the kitchen and bathroom taps and the WC in the bathroom, then capped the open end in the airing cupboard to create a closed system on the cold pipe serving the kitchen and basin taps. Compressed air was introduced into that pipe and pressure was observed to be dropping quickly, confirming an active breach in the line.

With pressure loss confirmed, acoustic equipment was deployed alongside the compressor to listen for the escaping air through the floor. The signal was loudest in the area between the kitchen island and the fridge, giving a precise enough location to justify targeted tile and screed removal.

Tracer gas was considered but ruled out, as the small hole the customer had already dug under the island would have allowed gas to escape and compromise the result — compressed air and acoustics alone were sufficient for this internal leak detection job.

Investigation Process

1. 1
   External meter checked

   With the customer's capped pipework in place and all other supplies running, the external meter showed no movement, confirming no active loss beyond the isolated section.

2. 2
   System isolated and capped

   The open end in the airing cupboard was capped, and the hot feeds to the kitchen and bathroom taps along with the bathroom WC were isolated to leave a closed cold-pipe section for testing.

3. 3
   Compressed air introduced

   Air was charged into the cold pipe feeding the kitchen and basin taps. Pressure dropped quickly, confirming a breach in the line.

4. 4
   Acoustic detection carried out

   With the compressor maintaining pressure, acoustic equipment was used to listen through the kitchen floor. The signal was loudest in the area between the kitchen island and the fridge.

5. 5
   Tracer gas ruled out

   Tracer gas was considered but not used — the small hole already dug by the customer beneath the island would have allowed gas to escape, making the method unreliable at that location.

6. 6
   Tiles and screed removed

   Four or five tiles and the concrete screed beneath were lifted at the identified location between the island and the fridge.

7. 7
   Split pipe found and cut out

   A section of 15mm copper pipe feeding the fridge was found to have split. The damaged section was cut out and removed.

8. 8
   New pipework fitted

   A new section of 15mm copper pipe and fittings was installed to replace the split section, restoring the cold supply line.

9. 9
   Airing cupboard pipework reconnected

   Four 22mm push-fit elbows and a short section of 22mm copper pipe were used to reconnect the pipework in the airing cupboard.

Result & Outcome

The leak was located beneath the kitchen floor between the island and the fridge, where a section of 15mm copper pipe had split. The combination of compressed air and acoustic equipment was precise enough to direct the excavation to a single targeted area, limiting tile and screed removal to four or five tiles rather than a speculative strip-out.

The split section was cut out and replaced with new 15mm copper pipe and fittings. Pipework in the airing cupboard was also reconnected using 22mm push-fit elbows and a short copper section as part of restoring the full cold supply. This is a typical outcome for internal leak detection work of this type — a precise location means the repair footprint stays as small as possible.

The engineer recommended allowing the exposed area to dry thoroughly before any re-screeding takes place, and that the pipes be wrapped in denso tape prior to being covered again to provide protection against future corrosion or movement damage.