Sewer Smell in the House? What It Means (Broomfield, CO)
A sewage smell drifting through your house is never pleasant. Most of the time, though, the cause is minor and easy to fix. We are The Drain Cleaning Company, a veteran-owned plumbing team serving Broomfield under Colorado license MP.03000945. We've walked into hundreds of homes chasing this exact smell, and we know how to trace it fast. Some cases are done in one visit — a running faucet fixes it. Others point to real damage further down the line, the kind a sewer line inspection in Broomfield, CO can confirm. This guide breaks down the common causes, the health risks worth knowing, a short list you can check yourself, and the point where it makes sense to call in a professional.
Why does my house smell like sewage?
A sewage smell almost always comes from one of these:
A dry P-trap under a sink, tub, or floor drain you rarely use
A loose or damaged wax ring seal under the toilet
A blocked or damaged vent pipe on the roof
A cracked, shifted, or root-blocked sewer line
Most of these are quick fixes. If the smell keeps coming back, especially alongside slow or gurgling drains, it often points to a problem in the sewer line itself.
If the smell keeps returning, a sewer line inspection in Broomfield, CO can pinpoint the exact cause.
Common Causes of Sewer Smell in Your House
Several things can cause a sewage smell in your house. A dry P-trap is the most common one we see. A cracked vent pipe, a bad wax ring, or a damaged sewer line can cause it too.
Dry P-trap in a sink, tub, or floor drain
Loose or failing toilet wax ring
Blocked or damaged roof vent stack
Cracked or root-blocked sewer line
Broomfield has a real mix of home ages. Newer neighborhoods run on PVC pipe that resists cracking. Older homes built decades ago may still have clay or cast iron lines that wear down over time. That mix means the likely cause often depends on when your home was built.
Dry Drain Traps — The Most Common (and Easiest) Fix
Every drain in your house has a curved pipe underneath called a P-trap. It holds a small amount of water at all times. That water blocks sewer gas from rising up into your home.
If a drain sits unused for weeks, the water in the trap can dry up. Colorado's dry air speeds this along, especially in guest bathrooms, basements, and floor drains that rarely see use.
The fix is simple. Run water in unused drains every few weeks to keep the trap full.
One thing we see constantly on Broomfield calls — a guest bathroom or basement floor drain that hasn't run water in weeks is almost always the source. Pour a bucket down it, and the smell is usually gone within the hour.
If running water doesn't clear the smell, it's time to look further.
When Sewer Smell Means a Bigger Problem With the Sewer Line
Some signs point to something more serious than a dry trap. Watch for a smell that keeps coming back, especially paired with slow or gurgling drains. If more than one fixture is affected at the same time, that's another red flag.
Colorado's clay soil moves as it gets wet and dries out. Front Range clay-shale, including the Pierre Shale found around the Denver metro area, is known for swelling and shifting more than typical soil. That movement puts pressure on old pipe joints and can crack them over time.
Tree roots make it worse. Roots don't create cracks on their own, but they find existing ones and grow inside them. Once inside, they widen the crack and block the flow. This shows up most often in mature Broomfield neighborhoods with older clay or cast iron lines. Freeze-thaw cycles add to the problem each winter, shifting the soil around buried pipe.
We recently ran a camera through an older clay line in Broomfield and found root hair filling almost half the pipe. The homeowner had noticed slow drains for months but figured it was just an old house. So the damage had been building for years before anyone called us.
Suspect a root intrusion or line issue? Book a Broomfield sewer line inspection to confirm before it gets worse.
Health Risks of Sewer Gas Exposure
Sewer gas is not just an unpleasant smell. It can contain hydrogen sulfide and methane, both byproducts of decomposing waste. In small amounts, hydrogen sulfide is what gives off that classic rotten-egg odor.
At higher concentrations, it can cause:
Headache or dizziness
Nausea or stomach upset
Eye, nose, or throat irritation
Trouble breathing in enclosed spaces
The U.S. Occupational Safety and Health Administration lists these among the short-term effects of exposure. Most homes never come close to dangerous levels, but ongoing exposure is still worth taking seriously.
This isn't cause for panic. Open a window, let the room air out, and get the source diagnosed. Most cases clear up fast once the actual cause is found.
What to Check Yourself Before Calling a Professional
Before you call anyone, run through this quick list. It only takes a few minutes, and it can save you a service call.
Run water in every sink, tub, and floor drain, even the ones you rarely use.
Check the base of your toilet for wobbling or dampness. That can mean a bad wax ring.
Step outside and check near the roof vent pipe for odor.
Note when the smell shows up. Is it constant, occasional, or tied to rain?
If none of these steps clear the smell, that's your sign to bring in a professional.
Why Broomfield Homes Benefit From a Professional Sewer Line Inspection
A camera inspection takes the guesswork out completely. We run a waterproof camera through your line and show you the footage in real time, so you see exactly what we see.
Colorado plumbers must hold a license through the state's Plumbing Board, which operates under the Department of Regulatory Agencies. That means anyone working on your sewer line has met state training and testing standards.
Broomfield's mix of clay soil and older clay pipe makes camera inspections especially useful here. What looks like a simple clog on the surface can turn out to be root intrusion or a shifted joint underneath.
What homeowners don't realize is how much a short camera run can save them down the road. We've caught small cracks before they turned into full backups more times than we can count, and catching a problem early almost always costs less than waiting.
Don't guess at the cause. Request a sewer line inspection and get a clear answer.
The Drain Cleaning Company is a veteran-owned plumbing team serving Broomfield and the greater Denver metro area.
Learn more about us at draincleaningco.com.
The Drain Cleaning Company 7180 W 117th Ave D, Broomfield, CO 80020 (720) 948-4175 Available 7am–10pm, 7 days a week
Save the number of a reliable emergency plumber Broomfield CO before you need one: (720) 948-4175.