Our sense of smell is a pretty remarkable early warning system. Long before our eyes see a problem or our ears hear it, our noses can tell us something’s not right. That’s why you notice the smoke from a grill before spotting the flames, or catch a whiff of spoiled food before opening the fridge.
At home, though, there’s one smell you hope you never detect: sewer gas. It’s a stench that can stop you mid-step, and it can signal a bigger problem with your plumbing system that may affect your health, safety, and comfort.
If you’ve ever wondered what sewer gas is, how to recognize it, and how to stop it from taking over your house, you’re in the right place. We’ll break it all down in a way that’s easy to understand.
What Is Sewer Gas?
At its core, sewer gas is a mixture of gases created by the breakdown of organic matter inside sewage systems. Common components include hydrogen sulfide, methane, ammonia, carbon dioxide, and small amounts of other substances. These gases develop naturally as waste decomposes.
Under normal circumstances, your plumbing system keeps these gases contained. Water-filled traps under sinks, tubs, and floor drains act as barriers, while vent pipes direct gases safely outside. If there is damage, a blockage, or water in a trap evaporates, the gases can escape into your living space.
How to Tell If a Smell Is Sewer Gas
Most people recognize the rotten egg smell of hydrogen sulfide, but sewer gas doesn’t always smell the same in every situation. Depending on its composition, it also might have an ammonia-like sharpness or even a faint gasoline odor.
You might suspect sewer gas if:
- The odor is stronger near a drain, toilet, or basement floor drain.
- It worsens after running water or taking a shower.
- It appears in areas near your septic tank, storm drain, or crawl space.
- It’s persistent, even after cleaning and using air fresheners.
Knowing how to tell if a smell is sewer gas can save you from breathing it in unnecessarily. If you suspect it, it’s time to look for the source and address it before it becomes a more significant issue.
Is Sewer Gas Harmful to Breathe in Your House?
The short answer is yes, it can be. Even if the smell isn’t overpowering, prolonged exposure to sewer gas can affect your health. Sewer gas is harmful to breathe in your house if the leak is ongoing, particularly in poorly ventilated areas like basements or bathrooms without exhaust fans.
Low levels can cause symptoms like headaches, dizziness, eye irritation, throat discomfort, and nausea. High concentrations — while less common in homes — can be dangerous, especially for children, older adults, or anyone with respiratory issues.
What you need to know if you smell sewer gas is that even a small leak should be taken seriously. Ignoring it won’t make it go away, and it could make the problem more expensive to fix later.
Common Causes of Sewer Gas in Homes
When sewer gas makes its way into your home, it’s usually the result of a plumbing issue that’s breaking the seal between your living space and the sewage system. Some of the most common causes include:
1. Dry or Empty Plumbing Traps
Every drain in your home — sinks, showers, tubs, and floor drains — has a U-shaped section of pipe called a P-trap. This trap holds water, which acts as a barrier to block sewer gases. If the water evaporates due to infrequent use or low humidity, there’s nothing to stop the gases from rising.
2. Damaged Vent Pipes
Your plumbing system uses vent pipes to equalize pressure and safely vent gases outdoors. If a vent pipe becomes cracked, disconnected, or blocked, it can force gases back inside.
3. Cracked or Corroded Pipes
Over time, pipes can develop leaks from corrosion, shifting soil, or root intrusion. Even a small crack can allow gases to escape, especially if the damage is near a basement, crawl space, or wall cavity.
4. Worn Toilet Seals
Toilets are sealed to the floor with a wax ring. If this ring deteriorates, gases can escape from the space between the toilet and the floor.
5. Septic System Problems
For homes with septic tanks, blockages or malfunctions can create backups and gas leaks. This can sometimes be the cause if you’re wondering what causes the smell of sewer gas in a house.
What You Need to Know If You Smell Sewer Gas
If you ever notice an unusual odor that might be sewer gas, take it seriously. Here’s what you need to know if you smell sewer gas in your home:
- Locate the source quickly: Start by checking drains, toilets, and floor drains. Look for signs of leaks, water pooling, or mold growth.
- Don’t mask the problem: Air fresheners and candles might cover the smell temporarily, but they don’t remove the harmful gases.
- Ventilate the area: Open windows and doors to let fresh air in while you track down the problem.
- Call a professional plumber: For stubborn odors or if you can’t find the source, schedule an inspection. This is especially important if you suspect a main line break. In that case, don’t hesitate to call Mike Williams for sewer line repair in Springfield or one of the surrounding areas in Central Illinois.
The Bottom Line for Homeowners
Sewer gas is one of those problems that can start as an annoyance but become a real hazard if left alone. Knowing how to tell if a smell is sewer gas, understanding that sewer gas is harmful to breathe in your house if there’s ongoing exposure, and acting quickly will help protect your health and your home.
If you’ve notice persistent odors, see signs of leaks, or experience health symptoms that could be linked to sewer gas exposure, it’s worth calling a professional right away.
Don’t Ignore the Smell. Call Mike Williams!
If you notice the smell of sewer gas, covering it with candles or air fresheners will not solve the problem. The only real fix is to locate the source and repair it. That is where Mike Williams can help.
Since 1976, our team has operated with the belief that all plumbing and HVAC services should be faster, cleaner, and better. We bring decades of hands-on experience to every job and treat each home like our own.
Here is why homeowners continue to trust us:
- We back every job with a 100% satisfaction guarantee.
- Our HVAC and plumbing team shares 180 years of combined experience.
- No project is too large or too small.
- We go the extra mile to deliver dependable, top-tier service.
- Same-day service is available for urgent plumbing and cooling problems.
- Financing options are available to make repairs more manageable.
- Our maintenance agreements include exclusive perks and cost savings.
Do you suspect sewer gas in your home? Don’t risk your family’s health. Mike Williams offers comprehensive plumbing services in Springfield and throughout Central Illinois, including sewer line repair. We will find the source, fix the problem, and help you get back to a safe and comfortable home. Give us a call today!