My Hot Water Smells Like Rotten Eggs

Did you know if you travel for weeks at a time this problem can develop with your water heater? My hot water from the sink in the master bathroom smells like rotten eggs. Cold water didn’t have any odor. Hot and cold water in the rest of the house smells fine too – no odor whatsoever, so I knew it was the water heater under my sink that was the culprit.

I have a small separate water heater just for my master bathroom sink because since it is the furthest fixture from my main water heater, it was taking several minutes for the hot water to come out of the faucet. Instead of constantly wasting water waiting for hot water when I brush my teeth or wash my face, I installed a small water heater that fits in the cabinet underneath the sink. I have sensitive teeth so refuse to brush my teeth with cold water because it is simply too painful to do so!

The sulfuric smell that developed while I was travelling is caused by bacteria that react with sulfur in the water and a magnesium/aluminum rod in the water heater that produces a hydrogen sulfide gas resulting in the rotten egg smell. (Water softeners make this problem a lot worse by the way.)

How to effectively fix the smell yourself without an expensive plumber:

1. Shut off the cold water valve to the water heater.
2. Turn on faucet to dispense hot water. This relieves pressure and drains some hot water from the tank.
3. Detach the cold water supply line to the water heater.
4. Drain more hot water from the tank as needed to make room for hydrogen peroxide.
5. Pour 1 cup of 3% hydrogen peroxide for every 10 gallons into the water heater tank.
6. Reattach the water line to the water heater – don’t forget to use new plumber’s tape to ensure a water tight seal.
7. Turn on the cold water from the faucet and let the water run for a little bit.
8. Wait a few hours for the hydrogen peroxide to do it’s job – killing the bacteria and eliminating the sulfuric smell.

Problem solved….that is until I travel for an extended time once more, which may allow that bacteria to proliferate once again. Then I’ll have to do this process all over! (I’ve already had to do it once before, but that was to my main water heater.)