One simple way to determine if you have a water leak in your home is to examine your winter water usage. According to the Environmental Protection Agency, a typical family of four may have a serious leak problem if "their winter water use exceeds 12,000 gallons per month." If so, it's worth calling a plumber to detect where the leak is. You can also check your water meter before and after a two-hour period when no water is being used. If it doesn't read exactly the same, you may have a leak.