As we mentioned, most water heaters operate safely 24 hours a day, 365 days a year. Here are some simple guidelines and warnings for water heater safety:

• If it's been more than a year since you Temperature - Pressure relief valve has been tested you should test it. T & P valves are mechanical devices which means that they can fail or clog. This device is your last line of defense in case of a thermostat failure resulting in overheating of your tank.
• It does not matter how old your water heater is. The tank in our video was purchased new just for this demonstration.
•  Sputtering, spitting and spewing from your faucets as you turn them on could be a sign of your water heater overheating. This is especially true if the water heater has been sitting idle for a while. The spewing/sputtering can occur on either the hot or cold side of your faucet.
• Excessively hot water is a sign of a thermostat malfunction, a precursor to excessive pressure build up.
• A dripping or trickling T&P valve can mean that your water heater is overheating or over pressure.

• We used a new, 12 gallon water heater (typically, water heaters in homes are at about 4 times this size)
• For heating, we used a standard, 4500 watt heating element.
• We began with 0 (zero) pounds of pressure. Typical homes have between 40 and 80 pounds of pressure.
• As water heats, it expands which results in a pressure increase. In our demonstration, it took about 1 1/2 hours to rise from 0 to 410 psi which is the pressure at which the tank exploded.
• The water temperature was about 400 degrees. When the tank ruptured, the water erupted into a steam explosion.
• These are the same conditions that could exist if your thermostat became stuck "on" and your T&P was faulty.