Pressure reducers are used to lower high water pressure coming from the main to lower levels for household use. Any pressure above 80 psi can damage water heaters, appliances and piping and may cause the temperature/pressure relief valve on a water heater to open and allow water to flow out.

If you experience these symptoms, look to see if you have something like the pressure-reducing valve shown at right. If you don't, you might need one. If you do, use a water pressure gauge to make sure it hasn't failed.

Also test for thermal expansion, which can result when pressure reducers or backflow preventers are installed.