The water supply system or a wastewater system in a house or other building may have a leak in any of numerous locations, causing dripping out or spillage of the water.

There can be numerous causes of leaks. Leaks can occur from the outset even during construction or initial manufacture/assembly of fluid systems. Pipes,  valves, fittings, or other components may be improperly joined or welded together. Components with threads may be improperly screwed together. Leaks can be caused by damage

Often leaks are the result of deterioration of materials from wear or aging, such as rusting or other corrosion or decomposition of elastomers or similar polymer materials used as gaskets or other seals. For example, wearing out of faucet washers causes water to leak at the faucets

There are several methods for leak testing, depending on the situation. Sometimes leakage of fluid may make a sound which can be detected.

Plumbers often test for leaks after working on a water or other fluid system. A vessel or system is sometimes pressure tested by filling with air and the pressure monitored to see if it drops, indicating a leak. A very commonly used test after new construction or repair is a hydrostatic test, sometimes called a pressure test. In a hydrostatic test, a system is pressurized with water to look for a drop in pressure or to see where it leaks out. Helium testing may be done to detect for any very small leakage such as when testing certain diaphragm or bellows valves, which are made to be practically leak-proof. Helium and hydrogen have very small molecules which can go through very small leaks.

How to check for hidden leaks By Greg Chick: Leaks waste water and cause serious damage, especially w

here you can’t see them. Many leaks can also be of a small enough quantity that you would never notice them on your water bill. Small leaks can become big ones (big expensive ones!). In the photo to the right, the copper pipe failed from the inside, corroded completely through, and formed a leak, the water eroding the copper to form an even larger hole.


Greg demonstrates a very easy way to check for leaks by using an inexpensive pressure gauge (less than $10 at the home center). In the video you’ll see what it looks like when there is a leak and also when there is not one.

To do this, a gauge is attached to a hose bibb on the building side of the shut-off valve. Then, the valve is closed to trap pressure in the system. If there are no leaks the system will hold the pressure over night

. In this video, we demonstrate the leak rate with a slowly dripping faucet (though the leak could easily be a hidden one).

An important aspect for this type of test to work is that the shut-off valve makes a good solid seal. If you have a ball valve like this one, it’s sure to meet that requirement. These valves turn 90° to shut off and often have a lever handle as shown.

However, if your water shut off is a gate valve (as shown to the left), then a tight seal is not guaranteed. Test results that appear to show “no leaks” may actually not be the case. If the valve leaks close to the amount that the inside pipes are leaking then you will not be able to detect a leak in this case.

Time to complete up to 30 min, but you may want the test to run overnight.
Materials water pressure gauge, channel locks or other pliers
Costs about $10 (for the pressure gauge.)
Skill level easy

( Courtesy: www.diyplumbingadvice.com )

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