Barney’s Blog no 8 - Internal Water Leaks and Pipe Bursts

Internal leaks and pipe bursts are the most distressing and disruptive event for the household; and the worst thing is the gradual realisation that it was not the water that the children spilt, an overflowing bath, or caused by an overexcited dog. A damp patch on the wall that will not dry up, or a concrete floor that feels loose and crumbly underfoot, and a continuous damp smell, may be the first signs of an internal water leak.


If the building has a water meter and the water consumption is higher than usual, this may also be cause for concern.

Because internal water leaks may continue unnoticed for some time, the longer time they run, greater damage is caused and the owner will incur extra costs of water bills if the building is metered.

Water leaks in the street are usually found and traced by the local water utility and its contractors. The pipe from the street to the building is generally (but not always) under the ownership and responsibility of the building's owner or occupier. If the water utility decides that there is a leak on the service pipe, usually they inform the owner and the owner has to arrange the fix and repair.

Any internal leaks inside the building have to be sorted out by the building's owner/occupier.

About thirty years ago it was common to install the copper cold water supply and heating pipes below the top screed of a concrete floor when the house was constructed. Sometimes the copper pipes were adequately protected, but in several cases when I have been called in to assist recently, the protection was inadequate.

Cement alone is not likely to cause any damage, but the other chemicals in the cement mix can cause very localised reactions causing small areas of corrosion that weakens the pipe until it becomes a hole in the pipe. The water pressure does the rest.

A hole of 2mm cross section with a modest 1.5 bar water pressure will pass 75 cubic metres of water if it runs for a month. Mains pressure of 3 bar increase the volume to 138 cubic metres. Soon you have lost enough water to fill a moderately sized swimming pool, but certainly at this stage enough to saturate the floor of a room, and at this point the leak should "appear".

Finding and pinpointing the internal leak on hot water systems

Recently the extraordinary benefits of the Thermographic methods using Flir thermographic cameras that are now being distributed by Seba KMT UK, have become clear. Thermography is a process that provides images of the heat differences of an object and it is a very useful process to help in leak detection.

The route of hot central heating pipes is easily pinpointed, and marked by an assistant while the thermographic camera operator uses the built in laser pointer to pinpoint the line of the hot pipes. Very often an area of leakage shows up as a hotter spread around the pipe route. We were using the Flir e-60 thermal camera for this purpose.
The same techniques can be applied to leakages in the hot water system of a building.
A competent plumber should be able to carry out a pressure test to confirm whether the central heating system is leaking or not.
Changes in the dampness of a wall, floor or ceiling nearby, and "wet patches" can also be revealed, and the shape of the patch generally provides clues to the origin of the leak. The new Flir e series thermal cameras can be linked by wireless to a dampness meter and show readings superimposed on the thermal image.

Cold water systems

A leaking cold water supply pipe from the mains can cause a great deal of damage to the floor structure. But if it is leaking under the vinyl floor covering in the kitchen, the leak may not show for some time until the water or damp patches appear in another room.

We recently solved a leak of this type by using the new Seba KMT Hydrolux HL5000H2 equipment. This combines acoustic listening with a trace gas detection sensor for hydrogen/nitrogen tracer gas.

In this case the client had assumed that the leak was on the central heating system, and started excavation along the feed and return pipes, but an abundance of water and no obvious leak from this pipework caused them to ask our help.

On site we pressurised the central heating system using the tracer gas, but saw no pressure drop, suggesting that the central heating system was in good order, and not leaking.
The problem was quickly proved to be on the incoming water service pipe. After closing the water stop valve outside the house, the H2 tracer gas was put in to the water service pipe via a washing machine tap under the sink by using a suitable adapter. At this point the sheet vinyl floor covering was lifted and revealed glistening water on the surface of the concrete floor, across its entire surface.

We prepared the Seba KMT HL5000H2 with its hydrogen sensor and a few minutes later the hydrogen tracer gas was detected close to the sink unit, and then by using the ground microphone from the HL5000H2, confirmed the leak by hearing the loudest noise position of the gas bubbles escaping from the pipe under the concrete screed.

Excavation showed a hole in the copper pipe about 2 sq mm; and from the damage it had caused, it had obviously been leaking for a long time.

These methods solved this problem, but leaks of this type with copper pipes installed in the screed of concrete floors are increasingly familiar, and it seems that there is a waiting epidemic of corroded copper installed about 30 years ago.

In all cases a precise pipe locator such as the Easyloc and Vloc Pro equipment, are useful to prove the pipe route across the floor, and make the leak detection process more accurate and precise.

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