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When Your Water Heater Smells Like Rotten Eggs

by Gabby Hyman
Repair-Home Columnist

Not everyone has had the experience of having the smell of rotten eggs wafting from their water heater. But if you have, you won't forget it. Chances are good that the sulfurous smell is caused by anaerobic bacteria setting up quarters in the magnesium and aluminum elements of the heater, creating gas. It smells terrible, but is generally harmless. Before calling in a plumbing contractor, you may want to add a quick flushing procedure as part of your home improvement routine.

Most water heaters come equipped with what are called "sacrificial anodes." The moniker applies because these anode rods are comprised of metal that gives itself up to dissolving agents in the heater instead of allowing the corrosives to gnaw at more vital parts. In so doing, the anodes protect the heater, but they also emit hydrogen gas in the process that bacteria feed on.

Launch a Pre-emptive Strike on Bacteria
In many cases, you can nip the stench before it overwhelms your environment. You can call in a plumbing contractor to assess the anodes. If you're told to remove the anodes, be advised that it can stop the smell, but greatly speed up the degradation and rusting of your water heater.

Another option is to have them install an aluminum-zinc alloy anode. Check and see how many anodes there are in your current water heater. Some models employ two of them. While an aluminum-zinc anode cuts down on generating bacteria, it may not be effective if you're using a water softener along with the water heater. In most cases, it's better to try the flush first.

Turn off the cold water valve to the heater and open a hot water line in the bathroom or kitchen and drain some hot water from the tank. There's an access valve on one side of the tank. Pour several pint bottles of hydrogen peroxide into the access valve. It kills off the bacteria. Chlorine bleach works as well, but it can create gases and vapor you don't really want in your home.

You should run a little of the peroxide-water combination out of the open hot water lines, but keep the balance of the solution in the hot water tank for several hours to do the trick. Close it all up, run fresh cold water into the heater, let it flush through, and you're done!

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