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How Does Sewer Gas Affect Indoor Air Quality in a Damaged Home?

Last updated October 31, 2026

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The short answer

What Is Sewer Gas Made Of?

Sewer gas is a mixture of gases and compounds produced by decomposing waste in plumbing systems. Its composition varies, but it often includes methane, carbon dioxide, ammonia, and hydrogen sulfide. The presence of hydrogen sulfide gives it a characteristic rotten egg smell, which serves as a warning sign. Other components may be odorless but still hazardous to your health and indoor air quality.

The specific mix depends on what is in the sewer line and the conditions within your pipes. Methane is flammable, while hydrogen sulfide is toxic even at low concentrations. When plumbing is damaged, these gases can escape into your home instead of being safely vented outside. This creates an invisible threat that degrades the air you breathe.

Health Effects of Sewer Gas Exposure

Breathing sewer gas can lead to a range of short-term health symptoms. Common reactions include headaches, dizziness, nausea, and irritation of the eyes, nose, and throat. Your body reacts to the toxic and irritating compounds in the air. For individuals with asthma or other respiratory conditions, exposure can trigger more severe reactions.

Prolonged or high-level exposure poses more serious risks. Hydrogen sulfide can affect your sense of smell at certain concentrations, making the gas harder to detect. In extreme cases, it can lead to loss of consciousness or respiratory problems. If you or anyone in your home feels unwell, it's important to get fresh air and consult a doctor.

  • Headaches and lightheadedness
  • Nausea and loss of appetite
  • Eye, nose, and throat irritation
  • Fatigue and difficulty concentrating
  • Worsening of asthma symptoms
  • Loss of smell at high concentrations

How Damage Lets Gas Enter Your Home

Sewer gas enters a damaged home primarily through compromised plumbing. Broken pipes, cracked drain lines, or dried-out P-traps under sinks can create direct openings. The water in a P-trap normally blocks gas from coming up through the drain; if it evaporates or a leak empties it, the seal is broken. This allows gases to travel freely from the sewer into your living spaces.

Structural damage from water can also create pathways. Cracks in foundation walls or floors near sewer lines can let gas seep in. Furthermore, your home's heating and cooling system can draw in and circulate contaminated air from a utility space or lower level. This spreads the gas and its odors throughout the house, affecting air quality in every room.

Immediate Steps to Take

If you smell sewer gas, your first priority is safety. Ventilate the area by opening windows and doors to let fresh air in and push contaminated air out. Avoid using any open flames, sparks, or electrical switches, as methane is flammable. If the smell is strong or pervasive, it's safest to leave the home until a professional can assess the situation.

Next, try to identify any obvious issues. Check all sink, shower, and floor drains to see if their P-traps are dry; pouring water down them can temporarily restore the seal. However, a persistent smell usually indicates a more serious problem, like a broken vent pipe or sewer line. This is not a DIY fix and requires help from a qualified plumber or water damage pro.

Professional Restoration and Air Quality

Addressing sewer gas infiltration requires a two-part professional approach. A qualified plumber must locate and repair the physical break or leak in the sewer or vent system. This stops the source of the gas. Simultaneously, water damage restoration pros are needed to dry out any affected materials and clean the air, as the initial water event likely caused the plumbing failure.

The pros use industrial air scrubbers and ozone generators to remove odors and contaminants from your indoor air. They also address any mold or bacteria growth that sewer water or high humidity may have caused. This comprehensive restoration helps ensure your home is structurally sound and the air is safe to breathe again. Policies vary, and your insurer decides what is covered.

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Frequently asked questions

Can sewer gas make you sick long-term?

Chronic, low-level exposure can contribute to ongoing respiratory issues, fatigue, and persistent headaches. While serious long-term illness from typical household exposure is less common, any repeated symptoms are a sign of an unresolved problem. It's crucial to fix the source to protect your health.

Will airing out the house get rid of sewer gas?

Ventilation can dilute the odor temporarily, but it does not fix the source. The gas will continue to enter as long as the plumbing breach exists. Professional repair is necessary to permanently stop the gas and restore safe air quality in your home.

Who should I call for a sewer gas smell?

Start with a qualified plumber to diagnose and repair the broken pipe or drain. If the leak caused water damage, you will also need local water damage pros for drying, cleaning, and odor removal. They work together to solve the entire problem.

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