Why Your Hot Water Smells Like Rotten Eggs

Woman holding her nose

Eggs — what a great way to start the day!

Except when the eggs move off your plate and into the bathroom and lose their freshness.

Few things are less appetizing than the stench of rotten eggs, and when that stench comes from your hot water supply, well, do you really want to bathe in it? The shower from hell?

What Makes Hot Water Smell Like Rotten Eggs?

Fortunately, this dire olfactory situation isn’t a threat to health. But it is an assault on your senses, and if you’re like most people, you’ll want to correct it. Giving the devil his due may not include showers.

There’s a single reason for the rotten egg smell, sulfur bacteria — so-called because they produce sulfur — and there are two possible sources:

  1. Your water heater
  2. Your water supply

Door number 1 holds the grand prize. When your showers smell like a day at Sulpher Springs, 9 times out of 10, your water heater begs for a check.

1. A Water Heater’s Warm Water Can Incubate Sulfur Bacteria

Water heaters should be set to about 120 degrees F. Anything higher carries the risk of scalding at the other end of the pipe.

If  the setting seems low, it is — for bacteria. For humans, it’s more than enough for showers, dishes, and other household tasks where hot water is involved.

Sulfur bacteria thrive in that hot but not-too-hot environment, pitch their tents, and propagate. They have nothing better to do.

Why sulfer bacteria love hot water tanks

Your water heater’s anodes help to prevent corrosion. They also produce hydrogen ions that combine with oxygen to form sulfuric acid. That’s a breeding ground for bacterial growth.

The bacteria plant their flag on your water heater’s anodes, feast on hydrogen ions, and propagate faster than rabbits in springtime.

The bacteria produce hydrogen sulfide gas

Hydrogen sulfide gas is a by-product of the bacteria’s daily routine. It builds up in the heater, and when you turn on your hot water, it wafts out of the fixture like an Easter parade, complete with rotten egg stench instead of candy.

Dealing with sulfur bacteria

Bleach is one way to kill bacteria, but it corrodes the anodes and shortens their lifespan.

A better solution is to set your water heater to 160 degrees or more for several hours. This water temperature is high enough to kill bacteria; it’s also dangerous for humans and their pets. So if you take this approach, resolve to put all hot water activities on hold until you turn down the dial.

Draining and flushing your water heater routinely — at least once a year — will remove sediment build-up that promotes bacterial growth. It will lengthen your water heater’s life and keep it running optimally. But at this point, it won’t eliminate your rotten egg smell unless you apply chemicals or increase the water temperature to a point where you may not be comfortable.

So you may want to call a plumber for a service call. Plumbers have access to specialized chemicals unavailable to the general public. The plumber will treat the tank for bacteria, flush it, descale it, and replace any damaged or worn parts (like anodes).

2. Well Water Can Be a Bacteria Source

Well water is more likely than municipal water to contain sulfur bacteria. Municipal water is treated, especially with chlorine. Well water isn’t.

However, that doesn’t leave your city water supply off the hook. Depending on your location, your water may arrive without much chlorine left.

Old iron distribution systems can create an ideal environment for bacteria growth, which quickly depletes oxygen and chlorine. Then, when the water enters your house, it’s ripe and ready to stink things up.

3. A Water Softener Can Make Matters Worse

Softened water increases water’s conductivity, which also increases hydrogen sulfide production.

Water softeners themselves are welcoming hosts for bacteria. Softeners contain little oxygen; bacteria prefer oxygen-deficient environments.

With softened well water, a smelly water problem is likely unless you take aggressive measures to maintain your water tank.

What Can You Do If Your Water Smells Like Eggs?

  • Turn on the cold water for a smell test. Then do the same for hot water. This test will confirm or clear your water heater as a suspect.
  • Hire a professional to flush your water heater and sanitize it. Don’t attempt this as a DIY repair; you may damage the heater. Ask the plumber to replace your anode with a zinc-aluminum anode to reduce the odor problem.
  • A powered anode may help with a stubborn sulfur problem. This device uses electricity to produce chlorine dioxide, eliminating hydrogen sulfide without damaging anodes.
  • If you have a well and experience a consistent sulfur aroma, consider installing an ultraviolet light water treatment system to neutralize bacteria in the water supply before it reaches your house.
  • Finally, if all else fails, contact your municipal water supplier for assistance.



Related Links

Servicing Southern California

We at Orange Coast Plumbing, Heating & Air Conditioning can work around your busy schedule. 


(714) 953-1111



1506 N Clinton St., Santa Ana, CA 92703
Service offices located throughout Orange County

*No walk-ins permitted | CA License #596002

service technician assisting residential homeowner signing on tablet

Get $25 off any service when you schedule online or by phone