Sewer Gas Smell: 8 Common Causes and When To Call a Professional

No one wants strong, unpleasant odors in their home. But when it smells like sewage, it might be a warning sign that something is wrong with your drainage system. Ignoring it could put your health and property at risk.

If you’re dealing with a sewer gas smell in the house, understanding the causes and knowing when to call for help can prevent serious damage and dangerous exposure.

What Is Sewer Gas?

When biodegradable waste in sewer systems breaks down, it releases gases such as methane, hydrogen sulfide, ammonia, and carbon dioxide. These combined cause foul odors and pose serious health risks.

In normal situations, your drainage system is designed to keep sewer gas from entering your home. However, if the system fails for any number of reasons, sewer gas can leak indoors.

Is a Sewage Smell in the House Dangerous?

It can be, as exposure to sewer gas may cause:

• Headaches or dizziness
• Nausea or vomiting
• Fatigue or breathing irritation
• Eye and throat irritation

In high concentrations, gases like methane are flammable, making sewer gas leaks a serious safety concern. 

8 Common Causes of a Sewer Gas Smell in the House

1. Dry or Empty P-Traps

Drainage pipes have P-traps, curved sections that hold water, to prevent sewer gases from entering. If a drain isn’t used often, water can evaporate, allowing odors to pass through the pipes and into your home.

2. Cracked or Damaged Sewer Pipes

A break or crack in sewer lines can release sewage water and gas into surrounding areas, such as walls, crawl spaces, or basements. This is a common issue in older homes.

3. Blocked or Clogged Vents

Plumbing vents regulate air pressure in drainage systems and release sewer gases through the roof. If this is blocked by debris, leaves, or bird nests, pressure can build and force gas back into the home.

4. Sewer Line Backups

Partial or full sewer backups can push gas – as well as sewage water – through drains, toilets, or floor drains. This is often accompanied by slow drainage.

5. Loose or Damaged Toilet Seals

If the smell is coming from the toilet, it could be due to a failed wax ring. Sewer gas may escape around the base, even if there are no visible leaks.

6. Improper Plumbing Installation

DIY or improperly installed plumbing may lack proper venting or traps, allowing odors to escape indoors.

7. Mold or Bacterial Growth

In some cases, what might seem like sewer gas is actually bacterial buildup in drains or HVAC systems. 

8. Septic System Issues

Homes with septic systems may experience odors from tank overflows, drainfield failures, or ventilation problems.

How To Tell If the Smell Is Getting Worse

Sewer gas smells shouldn’t be ignored if they:

• Lingers for days
• Becomes stronger over time
• Is noticeable in multiple rooms
• Is accompanied by slow drains or gurgling sounds

These are signs the issue may be spreading beyond a simple plumbing fix.

What To Do If You Smell Sewer Gas

If you notice a sewer gas smell in your house:

1. Open windows to ventilate the area.
2. Run water in unused drains to refill P-traps.
3. Avoid using chemical drain cleaners.
4. Do not attempt major plumbing repairs yourself.

If the smell persists, leave it to the professionals to address it.

Who To Call for Sewer Gas Smell Problems

While plumbers can address minor issues, persistent sewer gas odors often indicate deeper problems that require professional restoration services.

Restoration 1 of Oak Harbor specializes in identifying hidden sources of sewage odors, sewer backups, and contamination. Our team uses advanced detection equipment to locate leaks, damaged pipes, and affected areas, even when the source isn’t visible.

Contact Restoration 1 of Oak Harbor immediately if:

• The smell is strong or worsening.
• You experience health symptoms from the smell.
• There has been a sewer backup or overflow.
• Odors continue to linger even after basic plumbing checks.

We provide fast, reliable service to protect your home and your health, including:

• Sewage cleanup and sanitation
• Odor removal and air purification
• Structural drying and decontamination
• Emergency response services   

Don’t Ignore Sewer Gas Smells

A sewer gas smell is unpleasant, but it’s a warning sign that something is wrong with your drainage. Understanding the causes and knowing whom to call about sewer gas odors can prevent costly damage and serious health risks.

If you’re dealing with a sewage smell in the house that won’t go away, Restoration 1 of Oak Harbor is available 24/7 to help restore safety and comfort to your home.

Frequently Asked Questions About Sewer Gas Smells

What does a sewer gas smell like?

A sewer gas smell is often described as a strong, rotten-egg, sulfurous, or sewage odor. It can also smell musty or like decaying waste. If the smell persists, it usually indicates a plumbing or sewer issue that needs immediate attention.

Is a sewer gas smell in the house dangerous?

Yes. A sewer gas odor in the house can be dangerous, especially with prolonged exposure. It may cause headaches, nausea, dizziness, and breathing irritation. In high concentrations, methane gas can also pose a fire or explosion risk.

What causes a sewage smell in the house?

Common causes include dry P-traps, cracked sewer pipes, blocked plumbing vents, sewer backups, damaged toilet seals, or septic system issues. Even minor plumbing failures can allow sewer gases to enter your home.

Can sewer gas make you sick?

Yes. Sewer gas exposure can lead to flu-like symptoms, eye and throat irritation, and fatigue. Children, elderly individuals, and those with respiratory conditions may be more affected.

Who to call for sewer gas smell problems?

If basic fixes don’t resolve the issue, who to call for sewer gas smell concerns depends on the severity of the situation. Persistent odors, health symptoms, or signs of sewage contamination require professional help. Restoration 1 of Oak Harbor can identify hidden sources, remove contamination, and restore indoor air quality.

When should I call a professional for sewer gas odors?

You should call a professional if the sewer gas smell lasts more than a day, worsens over time, appears in multiple rooms, or follows a sewer backup or water damage event. Seek immediate medical attention if anyone in the home feels unwell.