I have a shutoff valve on the cold side of the water heater inlet. I also have a water main shutoff valve coming from my well. Are the cold and hot water lines in the house independent of each other and can I leave the main water valve open and just shut off the valve on the inlet side of the tank, therefore allowing me to drain the tank while still having water to the cold side of the house?

  • A picture would be thoroughly useful.
    – MonkeyZeus
    Mar 13, 2020 at 14:14
  • Remember to shut off the power/gas to the water heater first, and you might want to let it cool for a while if it's not so broken it's already cold. You'll also want to open at least one (or all) hot taps to improve the draining by letting air into the pipes/tank.
    – Ecnerwal
    Mar 13, 2020 at 14:26

2 Answers 2


Yes, you can leave the main on. Just shut off the inlet to the water heater. Your hot taps at the sinks won't work of course (the cold will), but then you can drain the tank. If the tank has some age on it, expect it to take a while too, lime often builds up and clogs the drain outlet.

  • 2
    Some faucet mixing valves could allow back flow into the hot side, so be sure to only open those in the completely cold direction. That's more to avoid water already in the hot lines from draining down since most of the water will go out the faucet.
    – BMitch
    Mar 13, 2020 at 14:38
  • Also, to help drain the tank open a few of the hot water faucets.
    – HoneyDo
    Mar 13, 2020 at 16:01

Yes they are completely separate, from some point after the source (in your case, your well) and before your hot water heater.

If you turn off the valve at the well it turns off all the water to the house, both cold and hot

If you leave the value open at the well and turn off the valve at the hot water heater, then the hot water will be turned off and the cold water will remain on.

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