Why does my bathroom smell like sewer?
A rotten egg or sewage odor that is strongest near a specific fixture, often worse after the room has been closed up.
Get A Free Quote
We reply fast. Same day when possible.
Key takeaways
- This is usually not an emergency, but it does not fix itself and it gets worse if you leave it.
- Most likely cause: Dry P-trap in an unused fixture or floor drain.
- Do this first: Run water in every fixture and floor drain for a minute to refill dry traps.
- Call right away if the odor comes with sewage backing up into a tub, shower, or floor drain.
- The repair starts with: Refill and test every trap in the room.
What it is
Sewer smell in the bathroom A sewer smell in the bathroom means sewer gas is entering the room, usually because a drain trap has dried out or lost its water seal, or because a vent or drain line has a crack or loose seal.
It is not usually an emergency, but sewer gas should not be ignored for long since it signals a broken seal somewhere in the drain system.
The short answer
A sewer smell in a bathroom means sewer gas is getting past a water seal that is supposed to block it. The most common cause is a dry P-trap in a rarely used shower, sink, or floor drain. Next is a failed wax ring under the toilet, then a blocked or broken vent stack, and finally a cracked drain line inside the wall or under the slab. Sewer gas is not just unpleasant, so track it down rather than masking it.
What it usually means
These are the causes we find most often, ranked from most likely to least.
- 1
Dry P-trap in an unused fixture or floor drain
Most likely
Evaporation empties the water seal in guest baths and basement floor drains.
- 2
Failed toilet wax ring or loose closet flange
Common
Gas escapes around the base of the toilet, often with a slight rocking motion.
- 3
Blocked or improperly terminated vent stack
Common
Without venting, traps siphon dry and gas pushes back through fixtures.
- 4
Cracked drain line in a wall or under the slab
Less common
Odor with no obvious source usually needs a camera inspection.
- 5
Failing main sewer line
Occasional
A broken or root damaged line vents odor back into the house.
What to do right now
- 1Run water in every fixture and floor drain for a minute to refill dry traps.
- 2Check whether the toilet rocks when you shift your weight on it.
- 3Note whether the smell is constant or only appears after a shower or a flush.
- 4Do not pour bleach down the drain and call it fixed. That hides the source.
When it is an emergency
- The odor comes with sewage backing up into a tub, shower, or floor drain.
- Multiple rooms smell at once and drains are also slow.
What the fix involves
If refilling traps clears it, the fix is done. If not, the work moves to resetting the toilet on a new wax ring and flange, clearing or repairing the vent, and running a camera through the drain to find a cracked line before opening any wall or slab.
- 1Refill and test every trap in the room.
- 2Pull and reset the toilet with a new wax ring where the seal has failed.
- 3Clear or repair the vent stack.
- 4Camera the drain line to locate cracks or a failing main.
What drives the cost
Every job is quoted before work begins. These are the factors that move the number on this kind of repair.
- Trap and toilet reset versus vent or drain line repair
- Whether a camera inspection is required
- Access through walls, ceilings, or slab
Related problems homeowners ask about
Why is my drain gurgling?
Bubbling or glugging from a sink, tub, or toilet, often when a different fixture drains or a washing machine empties.
Read this nextWhy is sewage backing up into my shower?
Dark water or waste rising in a shower pan or tub, often when a toilet is flushed or a washing machine drains.
Read this nextWhy are multiple drains clogged at the same time?
Toilets, tubs, and floor drains back up together, water rises in the lowest fixture when an upstairs one is used, and drains gurgle across the house.
Read this next
Read more on this
This page is for triage and dispatch. These guides go deeper on how the work is done and what shapes the price.
Licenses, credentials, and company proof
- Colorado Master PlumberLicense MP-18927
- Colorado State Plumbing ContractorLicense 2110
- Family Owned & OperatedServing Denver since 2006, 20 years
- Better Business BureauAccredited Business, A+ rating
- Angie's List Super Service Award2012 through 2017
- Serving Denver since 2006Residential and commercial properties across the metro
Tell us what is happening
Send the details and we will get back to you with next steps and a free quote. If it is urgent, calling is faster.
Get A Free Quote
We reply fast. Same day when possible.
Before you book: pricing, timing, and guarantees
Straight answers on what sewer smell in bathroom work costs, how fast we can get out, and what stands behind the repair.
More plumbing help from Afford-A-Rooter
- Drain GurglingA gurgling drain is an early warning. Learn the ranked causes, what the sound says about your vent or sewer line, and when to call a Denver plumber.View page
- Garbage Disposal HummingDisposal hums but will not spin? Learn the ranked causes, the reset button and hex key steps, and when the unit needs replacing in Denver.View page
- Frozen PipesFrozen pipes in a Denver home? Learn how to spot a freeze, thaw safely, avoid a burst, and when to shut off the water and call for help.View page
- Burst Pipe EmergencyA pipe burst in your Denver home? Shut off the main, kill power to wet areas, and call for 24/7 emergency plumbing. Here is the full sequence.View page
- Brown Or Discolored WaterBrown, yellow, or rusty water in a Denver home? Learn the ranked causes, the hot versus cold test, and when the pipes or water heater are at fault.View page
- Water Bill Suddenly HighA spiking water bill usually means a hidden leak. Learn the meter test, the ranked causes, and how a Denver plumber locates the leak without digging blind.View page
Stop guessing and get it diagnosed
Family owned, licensed Colorado master plumbers serving the Denver metro since 2006.