There is a leak detector on your water meter. It's the little red dial in the bottom left-hand corner of the top of the meter. This dial spins when water is being used. If there is no water being used in the house or outside, that dial should not be turning at all. If it moves at all, there is something leaking in the house. It may be a toilet, a faucet (inside or outside faucet) or at the bathtub. Most of the time, the toilet is the culprit. You can't always hear it or see it. You can check the toilet if it has a shut off valve to the toilet itself. Shut off the water supply to the toilet and then check the leak detector, if it stops turning, then the toilet has a leak. There are also dye packs available at the water office to use in the tank of a toilet to help detect a leak at no cost to the customer.