I just had a plumber install a new 50 gallon water heater, but the cold water pipe is installed to the hot side (the left pipe when facing the front of the heater) and the hot water pipe is installed to the cold side (the right pipe when facing the front of the heater). Is this ok? I thought that the cold water pipe had to go into the cold intake value and the hot water pipe would be connected to the hot value.

So I called the plumber and he said that everything is installed correctly. And he wouldn't change the plumbing.

  • 1
    Do you get hot water at the fixtures? Why do you think it is not correct? Could you be looking at the back of the water heater?
    – Tester101
    May 22, 2012 at 19:57
  • I get hot water, but the top of the water heater is marked "hot" and "cold" but the pipes are the opposite temperature.
    – James
    May 22, 2012 at 20:06
  • 1
    Can you follow the pipes to see where they go?
    – Tester101
    May 22, 2012 at 20:18
  • I've seen heaters that just have tags that slip over the pipes to indiciate hot/cold - are the hot/cold indicators removable? maybe they are switched and not the pipes
    – Steven
    May 22, 2012 at 20:44
  • Can you post a picture?
    – Bryce
    Jan 17, 2014 at 16:58

5 Answers 5


Yes, reversing them would be a bad thing. The cold water should be entering the bottom of the tank, the hot output at the top:

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I'd insist that the plumber fix this. But if they won't, I'd suggest picking up a pipe cutter, some sharkbite connectors, and just fix it yourself. Shouldn't take more than a half hour to do so.

  • 4
    +1 Good Answer, it will make your heater a lot less efficient and cause you to run out of hot water a lot quicker, this is due to the mixing affect when water is entering the top of the water heater instead of the bottom and also the hottest water will obviously be at the top of the heater.
    – UNECS
    May 22, 2012 at 22:33

I wonder.....are there some water headers made where the cold water dip tube can be dropped into either pipe from the top of the unit?

Strange I know answering a question with another question.

Such swappable scheme would lend itself to some replacement installations where the Hot/Cold lines of the existing plumbing are opposite to the factory default H/C pipes of the heater. A quick swap of the dip tube would solve this problem nicely.

I have had heater installations in previous homes where the water lines to the heater were fixed pipes attached to the heater without flexible couplers. As such, without it being a big plumbing project, it was far more convenient to redo the coupler pipes directly.

  • Often the dip tube is plastic and replaceable. It should be reasonably easy to swap sides if both top fittings are the same and made to catch the flared top on the dip tube. Nov 14, 2012 at 6:14

Apparently yes, it does mater! This article explains that the hot water will not be produced to it's efficiency.

  • 5
    Your answer is right, but an explanation should be included in your answer. Links have a way of going bad over time.
    – BMitch
    May 22, 2012 at 20:46
  • The answer you link to says he has seen 2 feet of deposits build up in a tank in a period of a year... I sure hope that is a typo.
    – Kellenjb
    May 22, 2012 at 21:08

You can switch the dip tube to the other side and everything will work fine, however in certain areas it is not code to do that and will not pass a plumbing inspection

  • Not always -- some heaters have an anode in the hot port that will need to be switched around as well. Dec 26, 2015 at 0:50

if you toliet water is hot then yes its hooked up backwards

  • 3
    No, that isn't what the OP was talking about... Apr 9, 2016 at 22:55

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