Can sewer gas come up through drains?

Author: Prof. Benny Ward  |  Last update: Sunday, July 5, 2026

Yes, sewer gas can come up through drains due to plumbing issues or issues with installation. How do you test air for sewer gas? You can test the air for sewer gas using a gas leak detector.

Why is sewer gas coming up through my drain?

If your kitchen sink drain smells, especially if there is a sewer smell, you may have a dry P-trap. The P-trap is the curved portion of pipe under the sink. It is supposed to hold water, which creates a seal that prevents sewer gases from getting into your kitchen. There needs to be water in the P-trap at all times.

What are the symptoms of sewer gas exposure?

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.

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

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 do I find out where sewer gas is coming from?

To begin, the first place you should look is your bathroom's drains. In your shower, tub, or sink, the sewage smell could be from biofilm buildup, a byproduct of all the products we use to clean ourselves. Or, you might look behind your toilet or sink in an area called the P or S trap to find the sewer gas source.

What to Do If You Smell Sewer Gas

How do plumbers detect sewer gas?

The best way to determine the source of the leak is to perform a smoke test. This is done with equipment designed specifically for performing this test and uses inert smoke that is induced into the drain and vent system through a vent or a sewer cleanout.

How long does it take to get sick from sewage backup?

How Long Does It Take to Get Sick From Sewage Backup? If you have become sick due to contact with sewage, you will likely start to develop symptoms within 1 to 3 days. If your symptoms are very severe and last longer than two days, you should call your healthcare provider for help.

Can sewer gas come up through the toilet?

Yes, sewer gas can come up through the toilet if there is a problem with the plumbing system.

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.

How do I get rid of sewer gas in my house?

How to Remove the Sewer Gas Smell from Your Home
  1. Identifying the source of sewer gas smell. ...
  2. Repair or replace damaged plumbing connections. ...
  3. Check floor drains and new plumbing to remove odor. ...
  4. Clean and deodorize drains. ...
  5. Using odor absorbers for sewer gas smell. ...
  6. Ventilate your home. ...
  7. Call a Professional Help for Sewer Gas Smell.

Is there a sewer gas detector?

A Sewer Gas Detector is a electronic handheld device that has a gooseneck with a sensor. The sensor detectors sewer gas coming from your drain in your shower, bathroom or kitchen.

How to neutralize hydrogen sulfide gas?

Chemical Scrubbing Techniques

These methods involve using chemicals like sodium hydroxide or amines to react with and neutralize hydrogen sulfide. The process effectively removes high concentrations of H2S, making it ideal for applications in petrochemical plants and refineries.

Does sewer gas come and go?

If you smell something foul, it's a sign you have a plumbing problem that needs attention. The smell is likely strongest at floor level or at the drain. While it might come and go (or you may become so used to it that you no longer notice it), it's not fixed even if the smell dissipates for a while.

Why is sewage backing up into my drains?

If the clog is in your main sewer line, it can cause sewage to back up into multiple drains and toilets throughout your home. Clogs can also result from flushing inappropriate materials, like paper towels, baby wipes, or sanitary products, which don't break down in water and can easily block your pipes.

How long does it take for sewer gas to dissipate?

If the sewer gas odor was caused by a dry P-trap, the smell should dissipate almost immediately. If you have any plumbing fixtures you rarely use, you can also easily prevent them from smelling like sewer gas by making sure to put some water down the drain every week or two.

Does homeowners insurance cover sewer back up?

While homeowners insurance protects you against some forms of unexpected water damage, water back-ups and sump pump overflows are usually not covered. You may purchase optional water back-up coverage that may pay for damages in the case of sewage back-up or a malfunctioning sump pump.

Can sewage fumes make you sick?

With higher concentrations of sewer gas, the health effects can be severe and may include loss of consciousness, respiratory distress, coma, or even death. Additionally, if someone already has a respiratory illness, even minor exposures to sewer gas can cause a serious health issue.

How do I know if I have a sewer backup?

If you are using one appliance, like the washing machine, and hear a toilet gurgling or bubbling, you may have a main sewer pipe backup. Another sign is when you run the bathroom sink and water backs up into the shower. Even if you hear minor gurgling after flushing the toilet, you should know that something is wrong.

Why does my bathroom smell like sewer gas but no leak?

Common causes of sewer smell in the bathroom can be from a dried-out P-trap, a blocked or damaged vent pipe or sewer pipe, a leaking toilet seal or a build-up of organic matter. Rotten-egg smell is a symptom of both septic gas, which leaks in through the plumbing, and toxic drywall, which off-gasses hydrogen sulphide.

How do I find out where my sewer gas is coming from?

Here are some of the most common causes for sewer gas leaks in a home.
  1. 1) Through the Toilet. The connection point around the base of the toilet will start to loosen over time. ...
  2. 2) Up the Shower Drain. ...
  3. 3) Clogged or Cracked Pipes. ...
  4. 4) Broken or Missing Clean-Out Plugs. ...
  5. 5) Dry or Clogged Drain Traps. ...
  6. 6) Roof Vent Pipes.

Will caulking a toilet stop sewer smell?

In addition, urine and water can get under your toilet and cause further damage. Apply caulking to form a protective coating around your toilet base and combat bad odors.

What are the symptoms of sewage sickness?

Germs and parasites may cause diarrhea, fever, cramps, nausea, vomiting, headache, weakness, or loss of appetite.

Is it safe to stay in a house with sewage backup?

Sewage backup is a serious issue that requires immediate attention and professional intervention. Due to the health hazards associated with sewage contamination, it is not safe to stay in a house with sewage backup.

How do you recover from exposure to sewer gas?

Treat symptoms such as headaches, nausea, and dizziness with over-the-counter medications recommended by healthcare professionals. Rest in a well-ventilated area and stay hydrated to aid the body in eliminating toxins. Use a cool compress or cold pack to alleviate discomfort associated with headaches or nausea.

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