To check for a leak you must first turn off all faucets inside and outside your house. Be certain the toilet is not flushed and the automatic ice cube maker is not operating when performing this task. If the indicator, sweep hand, or gallon indice are moving, and no water is being used in your home, you may have a leak somewhere. To determine the size of the leak, you may want to measure the volume of water that passes through the meter over a period of time. Checking Your Toilet for Leaks.
Toilets are notorious for their hidden leaks.
Most toilet leaks are at the overflow pipe. If overflow is the problem, a screw or knob on the valve or valve column will adjust the float arm down so the valve shuts off the water about a half inch below the top of the overflow pipe. If that doesn t fix it, the valve may be worn and have to be replaced. Otherwise, call a plumber. The flapper valve opens when you flush your toilet.