Rotten Egg Smell in House: 7 Causes and When to Worry

The smell of rotting eggs is an unpleasant scent that can signal something is wrong in your home. The sulfur-like odor has seven common causes, ranging from annoying to dangerous. If your house has a natural gas connection, evacuate and call the utility company to rule out a gas leak before trying to identify one of the other causes.

Rotten Egg Smell in House

The Source of Rotten Egg Smell in Your House

Here are the top causes and solutions for rotting egg smells.

Gas Leak

While natural gas and propane are clear and odorless, gas companies inject them with mercaptan, a chemical that gives them a sulfur-like odor, mimicking rotting eggs. The smell can alert you to a potential gas leak.

What to do: If you have natural gas or propane appliances or heat, and you smell sulfur in your house, evacuate the home. Call your utility company or the fire department to test for a leak. If no gas leak is detected, the rotten egg smell is coming from another source.

Sewer Gas from the Drain Pipes (Common)

If you notice the rotten egg smell every time you walk past a drain, you’re smelling sewer gasses. These odors are a mix of toxic and non-toxic gasses, most common in sinks you don’t use often. Water in the trap prevents sewer gasses from making their way up the drain pipe, so when that water evaporates after not using the sink for an extended period, you may notice a bad smell.

What to do: Get rid of sewer gas from drains by running water in your sink at least once per week. To help reduce the smell, clean your drain with boiling water, baking soda, and vinegar.

Drywall Off-gassing

If you live in the southern coastal United States and built a home or replaced drywall from 2005 to 2008, there’s a good chance you have toxic drywall. During this period, there was a drywall shortage, and contractors imported from China. The Chinese drywall was later found to produce off-gassing, which causes a sulfur smell and ruins copper piping and appliances.

What to do: If you suspect you have toxic drywall, check the copper wires of your HVAC system or appliances and look for black corrosion. Other signs include damaged electronic displays and satellite signals. The only solution is to replace your drywall.

Sewer Leak

Because of the mix of gasses in the sewer, a leak can create a rotten egg aroma in the house. If you step outside and the sulfur smell is even stronger, there’s a good chance a sewer line is cracked or busted. 

What to do: Call a plumber as soon as possible so they can locate and fix the leak.

Rotting Food or a Dead Rodent

Sometimes a rotten egg smell has a simple explanation…like actual rotting eggs. Check your fridge and pantry for expired or moldy food and toss it in the trash. 

If you’ve had rodent problems check your traps. If there are no rodents in the traps and you’ve used rodent poison, search at the site of the smell. Worst case scenario, a rodent has died inside your walls or ceiling.

What to do: If you suspect there’s a dead rodent stuck in the wall, call a pest exterminator. They can advise you and retrieve the dead rodent if applicable.

Well Water

Well water can develop a sulfur taste and smell due to the build-up of harmful bacteria. If your water is discolored, you have corroded plumbing, or you notice black slime in or around the well, don’t drink the water. 

What to do: Test your well water before drinking it. A well-water test will identify any issues, and you can treat the water or install a filtration system based on the test results.

Rotten Egg Smell When It Rains

Smelling rotten eggs after a rainstorm isn’t uncommon. If you have a septic tank, the heavy rainfall may overwhelm it, releasing hydrogen sulfide gas. Your soil also may contain small amounts of sulfur-containing minerals, which get released during heavy downpours.

If you don’t have a septic tank, the rotten egg smell can be due to an overwhelmed sewer system or clogged pipes.

What to do: If the smell is extreme or doesn’t go away quickly after the rain, consult a plumber.