Sewer Camera Inspection
Send a camera down the line to check its condition before a repair or home purchase.
Homeowner guide
Sewer Smell in the House in Commerce City, CO: Causes and Fixes
A sewer smell is rarely random. Dry traps, a failed toilet seal and a cracked pipe are the common sources, and the room where it is strongest tells you where to start.
By the Mile High Express Plumbing team · published
Why sewer gas gets in
A trap is a curved piece of pipe under every drain that keeps a small amount of water in it. That water blocks sewer gas from entering the house, but if the trap dries, leaks or is siphoned out, the smell escapes.
Drain lines are also vented through the roof. A blocked vent can pull water out of traps. A cracked pipe or a failed seal can leak gas directly.
Dry traps
Floor drains, guest baths and basement sinks that rarely see use are the top suspects, since trap water evaporates in a few weeks. Run a quart of water down the drain and float a spoonful of cooking oil on top to slow evaporation.
If the smell goes away, a dry trap was the cause. If it returns in a few days, the trap may be leaking or a vent may be blocked.
The toilet seal
A toilet that smells at the base, rocks or leaves moisture on the floor may have a failed wax ring. Sewer gas leaks around the flange.
Replacing the wax ring is a modest job, but check the flange and the subfloor. A toilet repair visit includes both.
Shower, sink and laundry drains
Soap, hair and food film in a drain create a sour smell that resembles sewage. Clean the stopper and the strainer, then flush with hot water and a cleaner. A drain cleaning visit clears film that you cannot reach.
A disposal that holds food residue can smell sour too. Grind ice and a slice of lemon, and run cold water.
Match the odor to its place
Start your search where the smell is strongest.
| Place | Probable source | First remedy |
|---|---|---|
| Floor drain or rarely used bath | A trap that has dried out | Add water, then a little oil |
| Foot of the toilet | Failed wax seal | Reset the toilet on a new ring |
| Kitchen sink or shower | Slimy film inside the drain | Clean the stopper, then flush |
| Several rooms or the basement | A vent or sewer line fault | Camera inspection |
Vents and sewer lines
If the smell is strong in several rooms, or if you also hear gurgling, look at the vent and the main line. A bird nest or debris in a roof vent can block it. A cracked or sagging sewer line can leak gas into a crawl space or basement.
A sewer camera inspection reveals the line's condition, including roots and sags. Request the video.
Basements and the main line
Basement smells often come from a floor drain or an ejector pit. The pit lid should seal tightly, and a vent should carry gas outside.
Mains belong to the district, and the pipe from your house to the main generally belongs to you. A smell paired with slow drains, or backups in the lowest fixtures, suggests the main line.
Smells that are not sewage
Utilities add a rotten-egg odor to natural gas deliberately. If that is what you smell, go outside and phone 911 or the gas utility from there. Do not hunt for the source or touch switches.
A sour smell near a refrigerator drain pan, a musty smell from a wet wall and a chemical smell from a water heater all have other causes.
When to call
Call if the smell persists after you refill traps and clean drains, if it comes with gurgling or backups, or if you see water stains. A plumber can smoke-test the system or run a camera to find the leak.
Do not ignore the smell. Sewer gas contains compounds that irritate the eyes and throat, and a persistent leak points to a pipe that needs repair.
Cleaning a drain that smells sour
Remove the stopper from the sink or tub and pull out the hair and film you find. Scrub the visible walls of the drain with a brush, then flush with hot tap water and a small amount of dish soap. Repeat if the smell lingers.
A baking soda and vinegar mix can loosen film, but it works only on what it touches. If the smell comes back within days, the film is deeper in the pipe, and a cable or jet cleaning is the better fix.
Vent stacks and rooftop causes
Drain vents rise through the roof so that air can enter the line and gases can leave. A nest, leaves or snow and ice can block the opening. A blocked vent causes gurgling, slow drains and traps that lose their seal.
Do not climb on a roof to check one in winter. A plumber can inspect the vent from the roof safely and clear it, or use a camera to see inside.
Smoke tests
In a smoke test, harmless visible smoke is pushed through the drain system. Smoke rising from the ground, a wall or a roof vent shows where the system leaks or a joint has come apart, which makes it a fast way to find a break you cannot see.
Tell the people in the building before a test, so that no one is alarmed by the smoke, and keep pets in a safe room.
Smell that comes and goes
A smell that appears after heavy rain, with a wind change or when the furnace runs can reflect a pressure change in the vents or the sewer. A smell only in winter, when you close up the house, can mean a trap that dried out from heating.
Note the pattern, the room and the time of day. Those details help a plumber find the source faster.
Common questions
Sewer odor questions
A dry trap, a failed toilet seal or a dirty drain are the most common reasons.
Persistent exposure can irritate eyes and throat. Fix the source and ventilate.
Yes. Run water for a minute, then add a little oil to slow evaporation.
That is the odorant added to natural gas. Go outside and phone 911 or the gas utility from there.
Services that help
Drain Cleaning & Unclogging
Open slow or stopped kitchen, bath, laundry and main drains, then work out the cause.
Toilet Repair & Installation
Stop a toilet from running, leaking or clogging, or set a new one.
Keep reading
Clay soil and sewer line problems
Front Range clay swells and shrinks. That movement can bend, crack or separate buried pipe. Here is what to watch for.
Basement sewer backup: what to do
Sewage in a basement drain or floor is a health hazard. Here is how to tell where the blockage is and what to do first.
Toilet won't flush
A toilet that will not flush is usually a clog or a tank problem. Here is how to tell which and what to try first.
Smell you cannot place?
Phone in and say where the odor is strongest. We will line up a local contractor.