You will need to check every plumbing fixture on your property, i.e., sink and tub faucets, outside sprinkler system, washer, water softener, etc. You will need to shut off the water supply to each fixture, one at a time and check the water meter for movement. If movement on the meter stops when the valve is shut, you will know that is the fixture that has the leak. There may be more than one leak at your property. Click here for more information about common causes of leaks.