Sewer Camera Inspection
Feed a camera through the pipe to view damage ahead of a home purchase or an excavation.
Homeowner guide
Sewer Smell in the House: Causes in Lafayette, CO Homes
Sewer gas smells like rotten eggs, and no one wants it in the house. The cause is usually simple: a dry trap, a loose seal or a blocked vent. Sometimes it points to a damaged pipe.
By the Lafayette Plumbers team ·
What the smell is
Sewer gas is a mix of gases from decomposing waste, including hydrogen sulfide. A trap, a U-shaped bend in each drain, holds water that blocks the gas from rising into the room.
If the odor is faint and comes from one spot, the cause is likely local. If it is strong, comes from several places or comes with gurgling drains, the sewer line itself may be at fault.
Dry traps
A floor drain, a rarely used sink or a spare bathroom can lose its trap water to evaporation. In dry Colorado air, that happens faster than people expect. Pour a quart of water down the drain to refill it.
A trap primer feeds some floor drains automatically. If one has failed, the drain dries out repeatedly. A plumber can replace the primer.
Wax rings and toilet seals
A wax ring seals the base of a toilet against the drain flange. When it fails, gas and sometimes water leak out around the base. A rocking toilet or a stain on the floor beside it supports this cause.
Resetting the toilet with a new ring fixes it. If the flange is cracked, a repair ring is added. See toilet repair for the procedure.
Blocked or missing vents
Drain pipes connect to vent pipes that rise through the roof. The vent lets air in so water drains smoothly and lets gas escape outdoors. A bird nest, ice or leaves in the vent can block it.
A blocked vent causes gurgling and slow drains along with odor. From the roof, a plumber can examine the vent using a camera or a cable.
Where the smell points
Location and pattern are clues.
| Where it smells | Likely cause | First check |
|---|---|---|
| Floor drain | Dry trap | Pour water into the drain |
| Beside a toilet | Failed wax ring | Check for rocking and stains |
| Across several rooms with gurgling | Blocked vent or main line | Call for a vent and line check |
| Outside near the yard | Damaged sewer line | Schedule a camera inspection |
Sewer line problems
A cracked or separated sewer line can leak gas into the crawl space, the basement or the yard. Tree roots, a belly in the line or a collapsed section may cause it. Repeated backups along with the smell point here.
Only a camera can show the pipe itself. What comes next is covered by sewer camera inspection together with sewer line repair.
Safety
Low levels of sewer gas are mostly a nuisance, but high levels can cause headaches and nausea, and the gas can be flammable. If the smell is strong, open windows, leave the area and call.
Natural gas smells different, because the utility adds an odorant. Should you notice it, step into the yard and ring 911 or the gas company.
Floor drains and washer standpipes
A basement floor drain or a laundry standpipe is a common source of odor. If the trap is dry or the strainer is clogged with lint, gas can rise.
Clean the strainer, refill the trap and run the washer drain for a minute. A trap primer can keep a rarely used drain wet.
Odor from a toilet seal
A loose toilet or a failed wax ring lets gas leak at the floor. You may notice a smell near the base, and sometimes a stain or soft flooring. Tighten the bolts gently and check for rocking.
If the toilet still moves or the smell remains, it likely needs to be pulled and reset with a new seal.
Prevention habits
Keep drains flowing by avoiding grease and wipes. Use enzyme or foaming cleaners only as directed, and do not mix chemicals.
A camera inspection every few years in older homes shows whether cracks or sags are developing before they cause smell or backups.
Checking the roof vent
With safe access, look at the vent stack for bird nests, leaves or ice. A blocked vent can cause gurgling as well as odor. Do not climb in wet or icy conditions.
If you cannot reach it, a plumber can clear it with a cable or a camera and check that the stack is intact.
Documenting the smell
Note the time of day, the room, whether it follows water use and whether weather matters. A pattern points to a trap, a vent or a line.
Share that record on the call. It helps the plumber bring the right tools and decide where to start.
Why the smell can come and go
Wind, temperature and appliance use change air pressure in the plumbing. A dry trap may only smell when a fan runs, and a vent problem may only show up during a storm. That is why a smell that seems random still has a cause.
Keep a short log of when you notice it. Patterns such as after laundry or during wet weather point to specific places, and the log helps a plumber decide where to look first.
Odor control that does not fix the cause
Candles, sprays and drain cleaners cover or irritate but do not repair anything. Chemical cleaners can also harm older pipes and are unsafe to mix.
Use them for comfort if you like, but treat the smell as a symptom. Tracing the source is what ends the problem.
Questions to answer before you call
Where is the smell strongest, which drains are used least, and has anything changed lately, such as a remodel, a heavy rain or a new appliance? A basement bath nobody uses is a classic dry trap.
Those answers cut the diagnosis time and often reveal a cheap fix.
Common questions
Answers on sewer smell
A dry floor drain, a cracked pipe or a failed seal are common causes.
In strong concentrations it can. A persistent smell should be checked.
Pour water into the drain. A thin layer of mineral oil floating on top keeps the water from evaporating.
If it is strong, or with backups, call. A faint smell can wait for the day.
Related services
Sewer Line Repair
Repair a cracked, rooted, sagging or separated sewer pipe without replacing more than necessary.
Drain Cleaning & Unclogging
Free up a backed-up sink, tub, washer drain or main line, then learn what caused it.
More plumbing guides
Roots invading the sewer line
Roots find tiny cracks in old sewer pipe and grow into a mat. Learn the signs, the options and how to stop it returning.
Fixing a running toilet
A toilet that runs nonstop quietly burns through water and cash. Most causes are cheap parts you can swap.
Causes of low water pressure
Weak flow can come from one clogged aerator or a failing regulator. Work from the simplest cause to the biggest.
Speak with the phone desk
Sewer smell that won't go away?
Call the line, say where it is strongest and whether drains are slow.
Call (720) 743-9476(720) 743-9476 · day and night