I wanna work on hot water line, have gas water heater, if i turn off cold water at water heater will it be ok to work on hot water line/pipes? will the pressure be released? i already turned on hot water faucet and no pressure, just wanna make sure.

1 Answer 1


Short answer: Yes

It depends on where the water heater is, relative to the pipes you want to work on. With a typical water heater in the basement, there will be very little pressure. If the water heater is on one level and you want to work on pipes a floor below then you may have to drain the entire tank. In any case, open up a couple of hot faucets and let them run until dry and you're all set.

Keep in mind that if you have mixing valves then you might have a problem of cold crossing to the hot side. If so, you may need to turn off the main supply instead of just the hot water, even though you're only working on the hot pipes.

  • 1
    I have to add if someone turns on another faucet both hot and cold, the water pressure is enough to push water out of the open line. I had a small flood when a home owner forgot I told her not to use the hot water but she could use the cold. I was at my truck threading pipe (galvanized system) and she started to fill a stock pot 3 gallons? There was probably 15 gallons of water on the floor by the time I came back in.
    – Ed Beal
    Jan 6, 2021 at 14:39
  • Yeah, single-handle faucets are a definite no under these circumstances. Jan 6, 2021 at 14:41
  • 1
    Probably obvious, but just saying: If the tank needs to be drained, be sure to shut off the gas supply first. Jan 6, 2021 at 15:44

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