I have cold water leaking into the hot water side of my hot water tank. In order to get hot water shower, I have to flush a toilet or turn cold water on at a different location.

With the cold water inlet side of tank closed, you can hear water coming in on the hot water side.

  • Could you include some photos of the tank and associated plumbing? Do you have a thermostatic mixing valve? What is the make and model of the tank?
    – Tester101
    Aug 26, 2015 at 17:01

1 Answer 1


If water is flowing back through the hot line with the shut off valve closed on the cold (inlet)line would indicate a leak in the tank or a faulty shut-off valve not completely closing. If the supply valve is off (closed) water flow stops. Check for air in the tank by opening the pressure+ relief valve with the cold valve shut. Water should sputter from it (hot! be careful) or air, initially and than water. Also, if possible, check for a H+C pipe reversal along the out going tank line. Primary locations to check would be the fixtures you are opening to increase the hot water temperature.

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