Pinhole Leaks

Pinhole leaks – Where do they happen?

From the rocky Montecito soils to the crumbly sands of Isla Vista these leaks can happen anywhere. There are a number of reasons for them, but are largely due to the instablility of the surrounding area.

What exactly are they?

A pinhole leak is a leak in a run of copper pipe. It is approximately the size of a pin head and seems to appear for no particular reason. While the majority of these leaks appear underneath slabs, they can appear in any environment. We have seen these leaks in commerical buildings, residential homes, and industrial complexes, and detecting them can be very tricky.

What causes a pinhole leak?

There are many theories on how these are caused. I will give my best explanation for the different types of pinholes I have seen throughout my career in Santa Barbara as a leak detection expert.

1) The leak is near a deformation in the shape of the pipe. We often find pinholes where the pipe is bent upwards in order to come through the slab and enter the wall of a building. When the pipe is initially bent, there may be slight kinks that cause variations of the pipe’s interior shape. Much like a rock in a stream, these variations cause a virtual eddy on the interior of the pipe as the water flows through it. At this point, the water is moving much faster than the surrounding water in the pipe and creates erosion on the interior walls leading to a leak. This is very common source of leaking or broken pipes in the rocky soils of Montecito and the San Ynez regions.

2) An unprotected length of copper passing through the concrete slab. Anytime copper passes through concrete, it must have some sort of protection around it. Typically this will be accomplished by a plastic sleeve but it can also be done using pipe insulation or something like 10 mill plumbing tape. You may hear a very subtle vibration in the pipes when water is flowing through them. This vibration along with small grains of sand in the concrete along with the pipe will dig a hole through the copper over time.

3) Near a fitting. We often see pinhole leaks near fittings. My theory is similar to that of a kink in the pipe. As water travels around the fitting, a disturbance is created in the water flow. This disturbance can speed up the water flow and increase the pressure on different walls of the pipe, thus causing erosion of the copper. Although often PVC, this type of leak is also very common in irrigation leaks around the greater Santa Barbara area and are a headache for the Montecito Water District and all suffering the wrath of its bills.

4) Pipe under a concrete slab, but close to a piece of rebar. While copper is a very good metal in that it is non-reactive to most things, it will create a dielectric interference when it comes into contact with iron pieces like rebar. Much like rust, a greenish white powder will be formed when the copper comes into contact with iron and begins to corrode both simultaneously.

5) A pipe run under a slab and filled in with soil that has a small aggregate in it. When we dig up a pinhole, we are always careful to look at what material was around it. We often find small rocks sometimes with sharp edges that were used as backfill and ended up touching the copper pipe. As explained earlier as the copper pipe vibrates overtime, these rocks will dig a hole through the copper thus causing a pinhole leak. We see this problem over and over throughout the Tri County Area. Homeowners big and small are in a rush to get things done, and take little notice of construction crews backfilling their pipes with rocks, cement, or near roots which have little to no problem creating leaks.

6) Why do they always seem to be in hot water lines? There are two reasons for this. First is that the majority of the time, we find pinhole leaks in the recirculation line which is a hot water line. Because there is a recirculation pump running on this line it has more flow on it than any other pipes in the house thus creating erosion on the inside of the pipe from the water flow. Second I feel is due to thermal expansion and contraction. The temperature of the hot water can vary because of the distance from the water heater and the rate at which the water is flowing. This means that the pipe is expanding and contracting as the temperature of the water inside it changes thus creating friction on the outside of the pipe against whatever it touches. While this isn’t as much of a problem in Santa Barbara as in other parts of the country, we have seen leaks in Ojai, San Ynez and Solvang where lower wintertime temperatures can create this same sort of strain.

Thanks for your time and again if you are having any problems with your water or gas lines give us a call. We have been servicing leaks in Santa Barbara, Goleta, and Carpinteria for nearly ten years and can point you in the right direction.

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