I smell rotten eggs.

Smell rotten egg odor? WARNING!!!
Having heard about the story in the website below, I AM EXTREMELY CAUTIOUS if I smell rotten egg smell…it’s hydrogen sulfide, [H2S] precisely the same gaseous, very explosive chemical produced by rotten eggs…(they don’t call it ‘rotten egg smell’ for nuthin!)…Especially if a home has been vacant for awhile, the sacrificial anodes (often aluminum or magnesium) can create H2S, (particularly in areas which have significant sulfur content…and esp. water wells) which can dissolve in the closed water/plumbing system. Any kind of spark, even turning on the dishwasher can cause an explosion.
Even if you do not smell the rotten egg H2S, there is still a possibility of the sacrificial anodes to produce odorless, extremely flammable hydrogen gas [H2].
In any event, any time I enter a home that has been vacant for awhile, I first let every faucet I can find run for quite awhile…smell for rotten egg smell…if I smell it, i let it run a long time before even thinking about flipping on any electrical switches, and ESPECIALLY before running the dishwasher, or using a burned-match-smoke test to check for water heater flue drafting.
I do believe the story embedded in the website below is a true one…it is certainly based upon sound chemical science.
Bottom line: Entering a home that has not had water running for awhile:
Larry (not Elmer Fudd)


I agree the odour can be from the anode, but
I have taken the anode out of my electric heater and still get the odour. But I know there is sulphite reducing bacteria in the water. I also have hard water fwiw.



An aluminum anode hex head will be flat on top, while a magnesium rod will have a bump, as in the photo above. The exception to that is Rheem and its sub-brands, Ruud/Richmond/General Electric. Rheem uses magnesium even though there is no bump on top of its anodes.