Install a water meter. You might be very surprised to find out how much water you are actually using. By           installing a water meter you can raise your awareness and consequently reduce your water intake.

1.If you already have a water meter, learn how to read it. Among other things, it can be very helpful in detecting      leaks. Read the meter once, wait an hour or two without running any water, and read it again. If it has moved,      something is leaking.
2.Many water meters have a small wheel or gear that turns fairly rapidly if any water at all is flowing. In the photo,    it's the little blue wheel. If you are sure all your water is turned off and you see this wheel moving at all, you have    a leak.
3.If your water meter is underground, you may need to remove debris from the face to read it. Squirt it with a bit      of water from a spray bottle.