Leak Detection
To determine if there is a leak at your home, read your meter before you retire for the evening, having used all the water you plan to for the night. Before using any water the next morning, read your meter again. If the reading is different from that of the previous evening, without having used any water, you may have a leak.
 
To check your service line for leaks, shut off the main valve in your home (this is probably located where the water comes into the house). Read your meter. Wait for half an hour, then read the meter again. If the reading has changed, you may have a leak in your service line.
 
Check toilets for leaks. Put a "leak detector" dye tablet or food coloring in your toilet tank. Do not flush the toilet for half an hour. If dye appears in the bowl, you have a leak that should be repaired promptly. Check faucets and pipes for leaks. Leaks waste water 24 hours a day, seven days a week. Even the smallest drip from a worn washer can waste 20 gallons or more each day.