Why does my house suddenly have a strong sewer smell?

Author: Marina Schumm Jr.  |  Last update: Friday, January 30, 2026

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.

How do I find the source of sewer smell in my house?

Or, you might look behind your toilet or sink in an area called the P or S trap to find the sewer gas source. Don't forget to check that your toilet is completely sealed to your floors since a loose toilet can let in sewer gas. The best-case scenario is a simple clogged drain.

Why does my house smell like sewage all of a sudden?

Sewer smell can indicate a blocked sewer line, but more likely it indicates a drain trap has dried out. Water filled traps under sinks and floor drains and water in toilets form a barrier to keep sewer gas from getting into the house.

Is it safe to stay in a house that smells like sewer?

Yes, the smell from a backup sewer in the basement can potentially harm you in several ways: Health Risks from Sewage Exposure: Sewage contains harmful bacteria, viruses, and parasites that can cause infections or gastrointestinal illnesses. Prolonged exposure to sewage can increase the risk of health problems.

Why does my drain smell like sewage but no leak?

That is a partially clogged main drain. It's has some of the venting blocked at times and is pulling the trap to get it which is why you smell sewer gas sometimes. You should snake or have it snaked by a drain service like roto rooter, or a plumber with a powered machine.

What to Do If You Smell Sewer Gas

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 are the symptoms of sewer gas poisoning?

Irritated eyes, nose, throat, and respiratory system, including tearing of eyes, cough, or shortness of breath. Effects may be delayed. Severe eye and respiratory irritation such as coughing and difficulty breathing. These symptoms may be accompanied by headache, dizziness, nausea, vomiting, and more.

How to test for sewer gas in house?

This can be accomplished with a sewer gas leak detector, or sometimes referred to as simply a gas leak detector. Other methods include calling in a plumber and he will undertake a smoke test to assess where, exactly, the leak may be in the pipes and also undertake a acoustic leak test.

How to detect where a smell is coming from?

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.

What does a dead mouse smell like?

A decomposing mouse smells like propane gas or rotting meat.

Can sewer gas come up through drains?

Floor drains and new plumbing fixtures, such as the basement or garage drains, can sometimes dry out and allow sewer gas to enter your home. Pour water into these drains to fill the traps and create a barrier that prevents sewer gas from escaping.

Who to call for chemical smell in house?

A qualified plumber, HVAC technician or remediation company can diagnose the source of the odor and take the necessary steps to eliminate it safely and effectively.

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.

How do I find sewer in my house?

It can typically be found in the basement, crawl space or garage. You will want to search for a pipe that is approximately four inches in diameter with a screw cap on the top that has a notch or square knob at the top. Note that some homes have an indoor sewer cleanout point, while others may be located outdoors.

How to tell if a P-trap is dry?

Identifying a Dry P-Trap

Here are the signs to look out for: Persistent sewer gas odours near sinks or floor drains. Drains that gurgle or make unusual sounds. Infrequently used fixtures, such as guest bathrooms or utility sinks, are familiar places for dry P-traps.

Why does my house smell weird all of a sudden?

Common Causes of Bad Odors in a Home

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.

Can I smell sewage in my house?

Plumbing vent: a sewage smell can fill your house if the vents freeze due to a temperature drop, or if a buildup of leaves clogs the pipes. Foul odors can also result from a crack in the vents. If this is the case, you will need a professional to pinpoint the vent leak and have it repaired.

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 figure out where sewer smell is coming from?

To find the source of that stinky smell, turn to the building's plumbing system. Check sinks, drains, toilets, and other plumbing fixtures for obvious signs of damage, leaking, or loose connections. It's also good to check sewer vents and the clean-out drain outside the building.

Is there a device that detects sewer gas?

Similar to a smoke detector, your sewer gas detector reacts when there are high levels of methane and/or hydrogen sulfide in the air. These aren't gasses normally found in your home. These are both produced from the act of waste breakdown.

How much does a sewer smoke test cost?

But what does a sewer smoke test cost? The answer varies depending on your location and the complexity of your plumbing system. Generally, you can expect to pay between $150 and $500 for a sewer smoke test.

Is sewer gas an emergency?

Answer: Only under extremely unusual circumstances. Although hydrogen sulfide is a toxic gas, it will not harm people at the concentrations that exist in a house with sewer gas odor problems. Studies have shown that hydrogen sulfide has a depressant effect on the central nervous system in concentrations above 150 ppm.

How to get rid of sewer smell in house?

The causes behind a sewer gas smell can be superficial or complex, depending on what is causing the odours to emanate from the drains or sewer lines. To eliminate sewer gas smell, you can use a combination of hot water, baking soda, vinegar, and even lemon to run through the drain to fix the problem.

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