116 – Pressure Testing a Tank for Leaks


To pressure test a tank for leaks, the only instrument you need is a water pressure gauge. The object of the test is to see if there is a significant drop off of pressure which would indicate a crack or hole in the tank.

To Conduct The Test, Follow These Steps:

  1. Install a pressure gauge on drain valve outlet and then open drain valve. This will give you a pressure reading inside the tank.
  2. Close cold water inlet to the water heater. Make sure all hot water faucets are turned off. This will create a closed system so pressure will build up in the tank.
  3. Turn thermostat up until main burner or heating element comes on.  Let pressure in tank increase 15 to 20 PSI. This will happen quickly, so be sure to keep an eye on the pressure gauge.
  4. When pressure rises, turn thermostat down to shut heater off. Watch pressure gauge to see if it holds pressure or drops off significantly.
  5. a) If pressure gauge drops off significantly and no leaks are found in any of the water connection fittings, then it is an actual tank leak.
    b) If the pressure holds for an extended period of time (10 – 15 minutes), then the tank is not leaking.
    c) If, when doing Step 3 you cannot get the pressure to rise, this may indicate that there is a hot water faucet open in the system or the actual hole or crack in the tank is significant enough to not allow any pressure buildup.

Always use caution when performing this test. Pressure buildup is a potentially dangerous situation.

This test should be conducted by a plumbing professional or a professional appliance service person.

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