What does it mean when your house randomly smells like rotten eggs?

Author: Prof. Kristian Nicolas  |  Last update: Saturday, February 7, 2026

Rotten Eggs The smell of rotten eggs is instantly recognizable and can be an indicator of a serious problem in your home. The two most common sources of a rotten egg smell are a natural gas leak, and escaping sewer gas. In its natural state, natural gas is actually odorless.

Why does my house suddenly smell like rotten eggs?

1) Rotten Eggs This smell is probably septic gas, unless you have a carton of eggs hiding in your living room. Septic gas has a strong, naturally occurring odor that smells like rotten eggs. The smell is hydrogen sulfide, which comes from sewage and indicates a potential issue with your plumbing.

Does carbon monoxide smell like rotten eggs?

Carbon monoxide doesn't smell like rotten eggs. Carbon monoxide gas is odorless—it cannot be smelled. Some myths surround ways to detect carbon monoxide, such as identifying the strong scent of rotten eggs. However, never ignore the “rotten egg” smell of natural gas.

Why does my house suddenly have a strong sewer smell?

These are the most common causes of sewer line clogs, broken or damaged sewer lines, and foul sewer odors in homes: Clogged drains and blockages. Blockages or backups from the city's sewer system. Tree roots that have intruded into the sewer line.

Should I leave my house if I smell rotten eggs?

If you do notice that "rotten egg" smell and suspect a natural gas leak, do not try to find the source of the leak yourself, but leave the building or area and call the 24-hour emergency Peoples number at 1-800-400-4271, or call your local emergency response number.

Why Does my House, HVAC, Smell Like Rotten Eggs? Conditioned Air Solutions, Huntsville AL

Is it safe to sleep in a house with sewer gas?

In extremely high concentrations, hydrogen sulfide can cause loss of consciousness and death. Suffocation: High concentrations of methane in enclosed areas decrease the amount of oxygen in the air and can cause suffocation. Symptoms of a lack of oxygen include: Dizziness.

How do I find out where a bad smell is coming from in my house?

If odors seem to be emanating from this part of your home, check the following locations:
  1. Trash Cans. Under counter trash cans are a frequent source of odors. ...
  2. Ovens. Baked-on foods in your oven can cause burning or smoking odors when your oven is in use. ...
  3. Cooktops and Hoods. ...
  4. Disposals. ...
  5. Dishwashers. ...
  6. Refrigerators. ...
  7. Cabinets.

Can sewer smell come and go?

Due to the frequent movement of water and waste through your plumbing system, and the varying use of different drains throughout the day, some issues can fluctuate. This means that you may only notice the symptoms of a problem, like a sewage smell, at certain times of the day or in response to certain action.

What do rotten eggs smell like?

An old egg isn't necessarily unsafe to eat, but it might not taste as good as a fresh egg. A rotten egg is one contaminated by common bacteria; it'll give off a putrid, sulfurous smell. In most cases, consuming a rotten egg will cause mild digestive issues, at most, compounded by a few days of cramping.

Does rotten egg smell always mean gas leak?

The smell of rotten eggs is a deliberate safety measure to alert homeowners like you to potential gas leaks. If you ever smell this in your home, it's a clear signal to leave the house immediately and investigate further, as it could indicate a gas leak.

Should I call 911 if I smell rotten eggs?

An additive (smell) is injected into natural gas to give it a rotten egg smell. If you are a natural gas customer, and you smell rotten eggs, call 911. You may have a natural gas leak.

How do I know if a smell is toxic?

How to tell if a bad smell is dangerous. It is not always easy to know if a bad smell is dangerous. If it smells like rotten eggs, sewage, or burning, it may be dangerous. However, some dangerous fumes such as carbon monoxide have no odor at all.

Why do I smell rotten eggs but no one else does?

Answer From Jonathan Graff-Radford, M.D. An olfactory hallucination, known as phantosmia, makes you detect smells that aren't in your environment. The odors you notice in phantosmia are different from person to person and may be foul or pleasant.

What does a dead mouse smell like?

A decomposing mouse smells like propane gas or rotting meat.

Who to call for sewer gas smell?

Sewer gas produces a very distinct rotten egg smell, caused when organic materials break down and decompose to form hydrogen sulfide. If you're unsure about the smell coming from your drains or sewers, call a licensed plumber who can perform an inspection or clear and clean blockages.

How to tell where sewer smell is coming from?

Where is the odor coming from? Check your home's drains, toilets, and plumbing fixtures for any signs of leaks or damage. Look for cracks, loose connections, or broken seals allowing sewer gas to escape. Additionally, inspect your sewer vents on the roof or outside your home for any obstruction or damage.

Does gas smell come and go?

Natural gas leaks are particularly likely to cause smells in small, enclosed areas where gas can build up. If the leak is outside, the smell may seem to come and go as the breeze blows it away. The other big sign to look out for is a strange noise.

Why do I randomly smell sewer?

All drain systems in your house must be properly vented to prevent sewage gasses from seeping into your home. A clogged vent pipe can prevent sewer-smelling air from leaving your home. This situation often results in leaking odors, and they typically come from the walls around the vent pipe.

Why does my house suddenly smell rotten?

Some common culprits include: Bacteria:Some strains of bacteria give off foul-smelling compounds when breaking down organic matter like food waste. Fungus: Molds and mildew emit volatile organic compounds and are often the cause when a house smells musty.

What does black mold smell like?

Toxic black mold growth has a more potent and identifiable smell, like the smell of decay, wet soil, or rot. Visually, it may be greenish-black, grayish-black, slimy, or more furry than other forms of mold or mildew.

Is there such a thing as an odor detector?

Odor sensors have been extensively used to detect gas leakage and in fields such as healthcare, mobility, and spatial environment control, in which the detection of low-concentration biogas and odor is crucial [3].

How do you test for sewer gas?

Smoke tests work by injecting a pleasantly smelling aerosol vapor into the sewer line in question. Once the line is full, the smoke will help show our plumbing professionals where the leak is coming from.

Can you stay in a house with sewer back up?

Quickly handling sewage backups is important for everyone's safety. If left untreated, it can cause more health problems and damage to the house. It's not something you should ignore. Living in a house with sewage backup is very risky.

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