Checking for household water leaks

This procedure enables you to determine if you have a water leak in your home either in a visible or invisible area without a pressure gauge. Temporarily isolate any hot water expansion tanks so they are not attached to the cold water system.


Part I - Testing the main street valve for leakage

Close off the main street valve and open a faucet. You may have to watch for a few minutes. If water is dripping the main street valve is leaking and the procedure can not be used.

Part II - Pressure testing a household water system

Make sure no water applicances are in use. Close off the main street valve previously verified as tight and not leaking for 15 seconds. Open the main street valve after the time expires. If you hear water rushing through the valve to repressurize the system you have a leak somewhere in the house.

If the 15 second test passes try again for longer durations of time. A normal system without leaks can hold the pressure, in theory, almost indefinately.

I like to test if mine is leak tight for 5 minutes.

This works because water is not compressible. If water drains or leaks out somewhere it gets replaced by the same amount of liquid to get back to original working pressure. The more you hear rush back into the system to pressurrize it, the more was lost.

Each leg of a system can be isolated to determine where a leak is in this method with the exception of expansion tanks typically attached to a water heater which have a moveable bladder.

Post edited by: jmborchers, at: 2008/09/02 23:52

Rather then shut the main which could be an old valve one would be better off looking at the water meter as many areas now require them to prevent waste.

The merer gives an accurate indication if there is water being wasted.

If water is being lost the most common cause is the toilet as many times these minor leaks are not clearly visible.

A simple test is to shut the water supply to the tank and leave it for an hour or so and then recheck the water level.

Drainage leaks are harder to diagnose with piping buried underground or in side walls

You can also make a quick and easy check by shutting off all the valves in the house (sink supplies, toilet supplies, washer, etc) and looking at the water meter. The meter has a little red triangle or little round needle gauge that spins very rapidly when water is passing through the meter. If there is a substantial leak, the triangle or needle turns so you can see it. If there is a minor leak, check the triangle or needle position and come back in a minute and check again. If it moved, you have a minor leak somewhere. Now the trick is to find it!

Damaging water leaks in your home are often quite easy to identify and fix. Major breaks in water pipes are noticed right away and the damage can be repaired rather quickly. What you may not realize is there can be many hidden leaks you cannot so easily detect. Water leaks account for higher water bills and structural damage.

Leaks generally are easy to find if it is from a hydronic or domestic water line, drainage leaks are the ones that give the experts a hard time as it could be grouting or a pipe giving up the ghost and these kinds of leak may take days to find and the water meter has NOTHING AT ALL TO DETECT THIS KIND of problem.

Also many of the older water meter do not have the triangle for detection