We have two hot water heaters in our house; one is in the attic and one is in our crawl space. We have a sulfur smell coming from the crawl space hot water heater, but the water smells fine coming from the attic hot water heater. Our cold water smells fine throughout the house, so we don't think the well water is the issue. The smell seems to be isolated to just the hot water heater in the crawl space. Any suggestions as to why one hot water tank would smell even though the other hot water heater smells fine?

  • Are they both tank heaters or both tankless? Regardless, just flush out the one in the crawl space. If it has an anode rod, replace it. It probably just hasn't been cleaned out recently enough and the location doesn't help. – TFK Feb 23 '16 at 12:32
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    Both water heaters have tanks. Neither are tankless. Also, I should have mentioned in my original post that both water heaters are new. We just built this house last year and moved in around November 2015. That's one of the reasons we find it odd that one water heater smells and the other doesn't. Our water (cold and hot) smells fine everywhere else in the house, except from the downstairs hot water heater. Thanks – Scott Long Feb 24 '16 at 14:22
  • Are they the same model? Again it might be best to flush it. It might say in the installation manual to flush it to remove the particles and 'new' smell from manufacturing. No bets on this though. Has the smell been around or did it just show up? – TFK Feb 24 '16 at 14:35

Your crawlspace Water Heater's Anode Rod is shot. This can be replaced at minimal cost compared to a new water heater by a plumber or HVAC guy or by you with some good straining on a long breaker bar...AFTER the Water Heater's been turned off, de-pressurized & very slightly drained.

Solid or Segmented Anode Rods, depending on "ceiling" clearances, can be obtained at Home Improvement or Plumbing Supply places. If one Water Heater went the other could be close behind & should be done as well, since checking it is the time to just replace it. There's nothing wrong or bad about replacing it too soon.

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    Thanks Iggy. Both of the water heaters are new. I should have mentioned that. We just built this house and moved in around November 2015. Knowing that both water heaters are new, would that change your recommendation? – Scott Long Feb 24 '16 at 14:19
  • Ah yeah Scott, doy! Sorry, I'm just kidding. Actually that doesn't change anything & the Anode Rod should be the only culprit. That tank may have been roughly handled getting it down there, which is quite plausible. The good news is that the installer should fix it for free & no need to do anything with the other one, yet. – Iggy Feb 24 '16 at 14:42
  • This was very helpful Iggy. You are 100% correct about fixing it for free. The plumbing company was at my house this AM to replace the entire unit since it was under warranty. Hopefully that solves it. I was worried I might have to fix it myself. Thanks for your time responding here. – Scott Long Feb 25 '16 at 17:15
  • Fantastic & it better solve it! Otherwise, you've got Chinese Drywall or a very bad Chef in the house. I'm so glad you didn't have to put up with it & pull anyone's teeth. – Iggy Feb 25 '16 at 17:41

The sulfurous hot water heater may have sulfate-reducing bacteria in it. These are typically removed by chlorinating the heater tank and its associated lines. Switching the anode inside from magnesium to aluminum (if applicable) is also suggested online; water reacting with a magnesium anode, if present, is more likely to make the H2 that the bugs live off. But don't ditch the anode entirely, as the reaction can also occur on the steel innards of the tank if they're exposed (and the steel innards will now begin to corrode, which the anode is supposed to prevent).

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