Gross Rotten Egg Smell at Home? 7 Reasons It Might Be Happening, and How to Fix It

If you were to compile a list of gross household odors, rotten eggs would be close to the top — so if you’re smelling that in your living space, it can’t be good. The odor most commonly comes from hydrogen sulfide, which is  a gas produced by the bacteria that feed on eggs (in the case of rotten eggs) or decomposing food and other organic matter in your drains or sewers (in the case of the household smell).

According to longtime (now-retired) plumber Andrew Miles, one of the main sources of the odor is stagnant water in the drain. “I’ve had many calls over my years in NYC where this was the case when apartments sit vacant for many months, and the water has been sitting in the pipes,” he says. Miles has a passion for water quality and currently blogs on waterfiltercast.com, a site devoted to water purification.

But wait! There are plenty of other ways for rotten egg smells to get into your home, so cleaning your drains might not fix the problem. In fact, the smell may have nothing to do with drains. Mercaptan, the chemical additive that gives a warning odor to otherwise odorless natural gas and propane, also smells like rotten eggs … so the smell may indicate a gas leak. Electrical problems can also produce rotten-egg smells, according to Justin Cornforth, CEO of South Carolina-based Ace Plumbing, Electrical & HVAC. 

So, assuming you didn’t throw eggs into the trash several days ago and didn’t leave the refrigerator door open while you were on vacation, you might have to do a little detective work to find the source of the rotten egg odor you’ve detected. Here’s a list of possibilities, ranging from the merely troublesome to the downright dangerous. 

Mold and bacteria love stagnant water, whether it’s pooling on the basement floor because of a leak or sitting inside the drain of a plumbing fixture you seldom use. Fortunately, this is easy to fix: Just clean up the pooling water or run water through the seldom-used drain.

“If odors from the pipes are still noticeable after a day, they may need to be professionally cleaned,” says Miles. “I would use an enzyme-based cleaner that would help break down any organic matter that may be lodged there.”

Of course, if pooling water is the result of a leak, you’ll also have to stop the leak.

That rotten-egg odor “could actually be rotten food stuck in the sink,” says Melanie Powers, president and CEO of Goodberlet Home Services. “If you are throwing everything in the garbage disposal, it may be causing a buildup and not properly getting rid of everything.”

Powers warns not to put all your food in the garbage disposal, since some foods — like coffee grounds, potato peels, and more — are more apt to clog. But if you do that anyway, you should at least clean your garbage disposal every so often. A combination of citrus peels and ice will clean and disinfect the grating ring, and that can prevent odors from developing in the first place. 

Even if you don’t have a garbage disposal, one or more of your drains could still be harboring bacteria. Microorganisms tend to colonize the top of the drain around the rim, where they get a steady supply of organic material like food, soap, and hair. Remove the drain cover and scrub the rim with soap and hot water to kill the bacteria and stop the odor.

Every drain in every house has a P-trap, which is the crook you see at the bottom of pipes. That P-trap is filled with water to keep sewer gasses inside the pipes (and not leaking out into your home).

When one of the P-traps empties, the result is an unobstructed path from the drain opening to the sewer. You can contain the sewer odors by pouring water into the drain to refill the trap, but this might only be a temporary solution. Here’s why:

It’s rare for P-traps to empty by evaporation, but it’s possible. More typically, water gets sucked out by negative pressure in the pipes, and this is usually the result of a blocked plumbing vent.

When a vent is blocked, you often notice the effects in more than one drain; some drains may gurgle, and the toilet may flush sluggishly.

The solution may be as simple as clearing obstructions from the main vent stack (a 2- or 3-inch pipe on the roof), but if that doesn’t work (or if you’re uncomfortable doing this yourself), then your best bet is to call a plumber to investigate. 

When you walk into a bathroom and smell rotten eggs, and you notice water around the base of the toilet, it’s a good bet the toilet’s wax ring has ruptured. This could have happened for more than one reason, but the most common is that the toilet wasn’t properly installed.

If the wax ring isn’t making proper contact with either the base of the toilet or the flange, which is the fitting around the waste opening in the subfloor to which the toilet is bolted, it can cause leaks that can lead to major water damage if not caught. 

If the situation developed recently, it can usually be fixed (by yourself or with the help of a pro) by removing the toilet and replacing the wax ring with a thicker one.

You might also have to add an extension to the flange (an inexpensive plumbing part available at most hardware stores) to bring it closer to the level of the finished floor.

However, if the toilet has been leaking for some time, the subfloor may be water-damaged, and a new wax ring probably won’t stop the leak. That’s obviously a bigger problem for which you’ll probably need professional help. 

“A less common cause of the smell of rotten eggs in your home is anode rod corrosion,” Cornforth says. “You know that’s the case if it happens when you run hot water.”

Every water heater has an anode rod, and its job is to attract ions that otherwise corrode the tank liner, producing hydrogen sulfide gas as a byproduct. You should replace the rod every five years or so, but most people forget, and as a result, the hot water supply can get stinky. It’s easy to replace an anode rod, and while you’re at it, you should also flush the tank to get rid of the contaminated water. 

Another possible source of rotten-egg smell that Cornforth mentions might be surprising. “If you smell rotten eggs near an electrical outlet, you probably have electrical issues,” Cornforth says. “This typically happens if the plastic components behind your outlet plate burn and emit odors similar to rotten eggs.”

Electrical outlets burn when they are worn out or one of the wires is making poor contact, resulting in sparks and electrical arcing that are hot enough to melt plastic. It’s important to replace damaged outlets immediately, because they are a fire hazard. 

A gas leak is the most serious source of rotten-egg odors, because what you are smelling is mercaptan in the gas itself. You might be able to follow your nose to find the source, which could be something as simple as a burner on the stove that someone forgot to turn off. You may also be able to trace it to a loose gas fitting that you can tighten with a wrench or, as Powers suggests, to a component of the AC system that needs attention. 

If the smell is pervasive and impossible to trace to a single source, you have the makings of an emergency. Don’t use any electrical devices — including light switches — to avoid sparks, and call the gas company immediately. Try to stay out of the affected area until the problem is resolved.