Sewer Smell in the House
Most sewer smells come from a dry trap in a floor drain or an unused sink, which lets sewer gas through. Pour water into every drain. Other causes are a failed toilet wax ring, a blocked vent or a cracked pipe. If the smell is strong and you also feel dizzy, air out the house and call a plumber.
Typical pro cost
$150 to $500
- Urgency
- Fix soon
- DIY difficulty
- Easy
- Time to fix
- 5 minutes to 1 hour
- Prices
- US typical range
Last reviewed September 2026
Signs it's this problem
- Smell near a floor drain or unused bathroom
- Smell around the base of a toilet
- Smell after a heavy rain or when drains run
- Gurgling drains with the smell
- Rotten egg smell only from the hot water
Common causes
Dry P-trap
Water in the trap blocks sewer gas. It evaporates in drains that are rarely used.
Failed toilet wax ring
A broken seal under the toilet lets gas escape at the floor.
Blocked vent pipe
Leaves, nests or ice block the roof vent so traps get siphoned dry.
Cracked drain pipe
Leaks gas into walls or the basement.
Water heater anode reaction
A rotten egg smell only in hot water is often the anode rod reacting with sulfur in the water.
How to fix it, step by step
- 1
Find the room where the smell is strongest.
- 2
Run water for 30 seconds into every drain, including floor drains, unused sinks and tubs.
- 3
Add a spoonful of mineral oil to rarely used floor drains to slow evaporation.
- 4
Check whether the toilet rocks or has water or stains around its base; if so, replace the wax ring.
- 5
If drains gurgle and several traps go dry, have the roof vent checked.
- 6
If the smell stays, a plumber can run a smoke test to find cracked pipes.
Tools and materials
- Bucket of water
- Mineral oil
- Flashlight
- Toilet wax ring kit if needed
Approximate DIY cost: $0–$25
Call a pro when
- The smell stays after all traps are filled
- Several drains gurgle or back up
- You suspect a cracked pipe inside a wall
Sewer Smell in the House cost
| Job | Typical cost |
|---|---|
| Plumber diagnosis and trap repair | $150–$500 |
| Replace toilet wax ring | $100–$300 |
| Clear a blocked vent pipe | $150–$500 |
| Sewer smoke test | $250–$500 |
Ranges are typical US prices compiled by FixHomeCost. Prices vary by region, home and contractor, so compare 2–3 local quotes.
Common questions
Why does my basement smell like sewage?
Usually a dry floor drain trap. Pour a bucket of water into the drain. If it returns, check the sewer cleanout cap and the sump pit for a missing cover.
Is sewer smell in the house dangerous?
Low levels are unpleasant but rarely dangerous. High levels of sewer gas can cause headaches, nausea and dizziness, so ventilate and fix the cause quickly.
Why does my bathroom smell like sewage after I shower?
A dry or slow sink or tub trap, a blocked vent, or a failed wax ring under the toilet are the usual causes.
Why does only my hot water smell like rotten eggs?
Bacteria react with the magnesium anode rod in the water heater. Flushing the tank and swapping to an aluminum-zinc anode usually fixes it.
Related guides
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