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Causes of Leaks

What causes a leak?

Leaks are a very curious fact of life. Many things contribute to leaks and the causes of leaks. First and foremost is the understanding that leaks generally occur by no fault other than a fault in the earth’s plate. As the earth is always moving and a somewhat rigid pipe is buried in the earth this eventually causes any weak spot in the pipe to begin to leak. Weak spots are for the most part fittings in the pipe, however, old metal pipe has weak spots in the pipe itself. Those awesome trees and shrubs you have in your yard are a major culprit in causes of leaks. The roots of a tree can “sense” water in a water line and will grow to the waterline. When I was a municipal water works operator a leak occurred on a 4 inch main line approximately 50 feet from where a contractor was removing a tree that was not more then 10 inches in diameter. The cause of the leak? One of the main “tap” roots had coiled around the pipe like a boa constrictor, causing the pipe to rupture when the tree was pulled out using an excavator. Rarely a leak can be caused by heavy truck traffic or a large piece of equipment driven over the line. Another cause of leaks is know as a “water hammer”, this will be explained below.


A water hammer is a surge of water caused by opening or closing a main valve too quick. The best description I have is when you are using your kitchen faucet sprayer and you release or let go of the sprayer. There is a thud and your sprayer hose jumps for vibrates. This is a smaller version of a water hammer. It this is done on a larger scale like turning off and then on your water meter when your line is empty the water hammer will cause a surge of up to three times your water pressure. So if you have 50 psi it will/could create 150 psi and damage your pipes, causing a leak. You should open a faucet when your water is turned off, this will give the air and water a chance to flow without being the cause of the leak. This is only applicable if you plan on turning your valve back on rapid rather than gradually. When your water is turned back on it should be done very slowly to ensure no hammer happens. This can be done by listening to your valve when the water is turned back on. You will hear the line fill. Once the line is full the valve can be opened fully. Watch a video here

Causes of Leaks
The cause of leak? A water hammer on a 1 1/2 inch PVC pipe.