Sewer smell in the house
A sewer smell inside the house usually means sewer gas is getting past a seal that's supposed to stop it. Most of the time that's a drain trap that has dried out in a sink, shower or floor drain nobody uses, or a toilet wax ring that has failed. Start with the easy fixes; they solve most of these. Pouring a little water down unused drains once a month keeps the traps full, and that's often all it takes to keep the smell away.
Why a house smells like sewer
Every drain has a trap, a curved section of pipe that stays full of water. That water blocks sewer gas from coming up into the house. If a drain isn't used for a while, the water evaporates and the gas comes through.
Toilets seal to the floor with a . If it fails, gas and sometimes water escape at the base. Buildup in sink drains and overflows can also smell a lot like sewer gas.
Where sewer smells come from
Water evaporated from a drain nobody uses.
Gas escapes at the toilet base.
Gunk in a sink drain or overflow.
A blocked roof vent can pull traps dry.
| Where | Likely cause | Fix |
|---|---|---|
| A guest bath or basement drain | Dry trap | Run water; refill it. |
| At the base of a toilet | Failed wax ring | Replace the ring. |
| One sink only | Buildup in the drain or overflow | Clean it. |
| Everywhere, with gurgling | Blocked vent | Call a plumber. |
Find the source, then seal it
- Find where it's strongestWalk through the house and sniff near each drain: sinks, tubs, showers, floor drains, the laundry and around each toilet's base. Guest bathrooms and basements are the usual suspects.
- Refill dry trapsRun water for about a minute in every sink, tub and shower that doesn't get used much. Pour a bucket of water into floor drains. If the smell fades within an hour, a dry trap was the cause.
- Check the toilet baseLook for water around the base, a rocking toilet, or a smell right at the floor. Those point to a failed wax ring, which needs the toilet pulled and a new ring set.
- Clean smelly drainsIf one sink smells, pull the stopper and scrub it and the drain opening with a bottle brush. Clean inside the overflow hole too. Gunk there can smell just like sewer gas.
- Check the cleanoutsLook for a loose or missing cap on any drain , often a round plug on a pipe in the basement, garage or crawl space. Tighten it by hand.
- Keep traps fullFor drains you rarely use, run water in them every week or two. A few tablespoons of mineral oil on top of the water in a floor drain slows evaporation.
Watch it done
- The smell fades within an hour of refilling traps
- No water or smell at any toilet base
- Cleanout caps are on and tight
Drains gurgle or traps dry out? The roof vent may be blocked.
If the smell won't go away
If drains gurgle when water runs elsewhere, or traps keep drying out even with use, the plumbing vent on the roof may be blocked. A plumber can check it without you going on the roof.
If the smell comes from the washer area, check that the washer's drain hose goes into a standpipe with a trap, and that the hose isn't sealed tight into it.
What a pro typically charges (a rough estimate; prices vary by area): A plumber typically charges $150–$350 to find a sewer smell. Replacing a toilet wax ring often runs $150–$300.
Find a plumber near you