Why does my house smell like sewer?

Wondering what's going on in there?

How your drains keep sewer smell out, in plain English

Your drains connect to a sewer or a septic tank. Those pipes are always full of smelly sewer gas. Two simple things keep it out of your house: water and air. A sewer smell means one of them is failing somewhere. Think of each drain as a door with a little puddle of water across the doorway.

Each number matches a step below.

The trap. Under every sink, tub, shower and floor drain, the pipe dips into a U-shaped bend (the P-trap). It holds a little water, and that water blocks sewer gas. If a drain isn't used for a few weeks, the water dries up. Then the smell gets in.
The vent. A pipe runs from your drains up through the roof (the vent stack). It lets air in, so draining water doesn't suck the traps dry. It also lets sewer gas out, high above the house. Some sinks have a small air valve under them instead.
The toilet seal. A toilet has a trap built in. Under it, a wax ring seals the toilet to the drain in the floor. If the toilet rocks or the wax gets old, sewer gas slips out at the base.
The cleanout. A short pipe with a screw-on cap gives a plumber a way into the main pipe. It may be outside, in the basement or in a crawl space. If the cap is loose or missing, gas comes straight out.
The main sewer pipe. Every drain joins one big pipe that runs out to the street sewer or a septic tank. If it clogs or cracks, drains slow down, toilets gurgle, and the smell can seem to come from everywhere.

Gas or sewer? Natural gas has no smell of its own. Gas companies add one that smells like rotten eggs. Sewer gas smells like rotten eggs too. So we don't ask your nose to tell them apart. A strong smell, a smell near anything that burns gas, or any doubt means gas: leave and call from outside. A mild smell coming right out of a drain is the plumbing.

And sometimes it's just gunk. Slime in a sink drain or its overflow hole can smell like sewage all by itself. That's the cheapest fix of all.

Does a glass of tap water stink, even in another room? That's the water, not the drain. See our guide to water that smells like rotten eggs. Smell at the washer's drain pipe? See a washing machine that smells. Water at the base of the toilet too? See a toilet leaking at the base.

Drains slow as well? See a clogged shower drain, a clogged kitchen sink or a toilet that won't flush. Kitchen sink smell near the disposal? See a garbage disposal that's not working.

Who to call

Rather not do it yourself? Call a plumber.

That's a fine choice. Maybe you're busy. Maybe you're selling the house and just want it done right. A plumber can track down where the smell is coming from and fix it.

$50–$250Plumber's service call

$100–$800Clear the main line

Most plumbers charge $45–$200 an hour, and some add a fee to come out.

Find plumbers near you

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What to say

Calling a pro? Here's what to say.

A few lines to read when they pick up, and the questions to ask before anyone comes out.

Before you call

Rent? Call your landlord first.

Home warranty? Call them first.

4.5 stars or more, and a license number.

Say this

Hi. My house smells like sewer. When's the soonest you can get here? And what's your fee for the visit? Does it go toward the repair?

Always ask

What's your fee to come out, and does it go toward the repair?
Do you charge by the job or by the hour?
Will you tell me the full price before you start any work?

Watch out if

They push a full replacement on the first visit for a small problem.
They won't give you a price before starting.
They add an emergency fee without telling you first.

Feeling pushed to decide on the spot? You can say no and hang up. You owe nothing for a phone call.

Know what's wrong before they come

Answer up to 5 quick questions. We'll give you the words a pro uses.

Answer the questions →

More of a list person?

Common symptoms, causes, tests and costs

Find the row that sounds like yours. The quick test is something you can do yourself in a few minutes.

What you notice	What it probably is	Quick test	Do it yourself	With a pro	Verdict
Strong rotten-egg smell, or a smell near a gas appliance or the meter	It could be a gas leak	None. Leave the house	Pro job	$50–$250	CALLSee the answer: It could be a gas leak
Someone feels sick, dizzy or headachy from the smell	The smell is strong enough to make you sick	None. Get into fresh air	Pro job	$50–$250	CALLSee the answer: The smell is strong enough to make you sick
A glass of tap water smells in another room too	It's the water, not the drain	Smell a glass of water in a room that doesn't stink	Free	Not needed	FIXSee the answer: It's the water, not the drain
Smell at a drain that hardly gets used. Gone after running water	A dried-out drain trap	Run water into the drain and wait a day	Free	Not needed	FIXSee the answer: A dried-out drain trap
The little hole under the sink's rim smells worst	Gunk in the sink's overflow hole	Put your nose right up to the overflow hole	Free	Not needed	FIXSee the answer: Gunk in the sink's overflow hole
Black or gray slime or hair on the stopper or in the drain	Slime and gunk inside the drain	Pull the stopper and look	Free	$100–$250	FIXSee the answer: Slime and gunk inside the drain
Sewer smell at the toilet's base. It may rock or leak	The seal under the toilet is worn	Gently rock the toilet and sniff at the base	Pro job	$50–$200	CALLSee the answer: The seal under the toilet is worn
Smell at a short capped pipe. The cap is loose, cracked or missing	A loose or missing cap on a sewer pipe	Look at the cap. Don't open it	Free	$50–$250	FIXSee the answer: A loose or missing cap on a sewer pipe
Smell at the pipe the washer hose goes into	The smell is coming from the washer's drain	Sniff the pipe behind the washer	Free	Not needed	FIXSee the answer: The smell is coming from the washer's drain
Drains gurgle. The smell comes and goes, or comes back after running water	The pipe that lets your drains breathe is blocked	Run water into the drain. Is the smell back in a day or two?	Pro job	$100–$200	CALLSee the answer: The pipe that lets your drains breathe is blocked
Smell at one drain that water doesn't stop. No trap, or a smell at the air valve	A missing trap or a worn-out air valve	Look under the sink for the U-shaped bend and the capped stem	Pro job	$50–$250	CALLSee the answer: A missing trap or a worn-out air valve
Smell all over. Several drains slow, toilets gurgle, or a soggy strip in the yard	The main sewer pipe is clogged, cracked or broken	Run the sink and a tub, flush, and watch the other drains	Pro job	$100–$4,100	CALLSee the answer: The main sewer pipe is clogged, cracked or broken
Water comes up in other drains. Sewage smell	The main drain is backing up	Run the sink and watch the tub or floor drain	Pro job	$100–$800	CALLSee the answer: The main drain is backing up
On septic: slow drains, gurgling, or wet, smelly or extra-green ground over the tank	The septic system needs pumping or repair	Walk over the tank and drain field. Look and sniff	Pro job	$290–$565	CALLSee the answer: The septic system needs pumping or repair
Smell at the street, a manhole or storm drain. The neighbors smell it too	The smell is from the city sewer	Walk to the street and sniff near the manhole	Pro job	$50–$250	CALLSee the answer: The smell is from the city sewer

2026 U.S. averages, rounded. Pro prices include parts and labor. Most plumbers charge $45–$200 an hour, and some add a fee to come out. Nights, weekends and big cities cost more. See all repair prices

Want proof it's the drain?

The glass-and-water test

Two quick checks tell you if the smell is the water, a dry drain, or something a plumber needs to fix.

Glass first. Fill a glass at the smelly sink. Carry it to a room that doesn't stink, and sniff it.
Then water in the drain. Run water into that drain for a minute or two. Floor drain? Slowly pour in a bucket. Toilet? Flush it twice.
Wait a day. Open a window. Check the smell again the next day.

The glass stinks: it's the water, not the drain. See our rotten-egg water guide.
The smell is gone: a drain trap had dried out. Run water in that drain every week or two.
It's back in a day or two, or drains gurgle: the vent may be blocked. Call a plumber.
It still smells right away: clean the drain and its overflow hole. Then take the questions at the top.

Not sure it's safe to stay inside?

Leave or stop right away if…

It's a strong rotten-egg smell, or any smell near a gas stove, furnace, water heater, dryer or the gas meter. Leave now. Call the gas company or 911 from outside.
You hear a hiss near a gas pipe or appliance. Treat it as gas.
Anyone feels sick, dizzy or headachy. Get everyone into fresh air. Call 911 if someone is very sick or passes out.
A strong smell suddenly fades while you're in it. At high levels, people stop smelling sewer gas. Get to fresh air anyway.
Sewage comes up out of a tub, shower or floor drain. Stop using water and call a plumber today.

Might be gas? Don't flip light switches, use your phone or light a flame inside. Make every call from outside.

Got a big sewer pipe quote?

Before you pay for a big sewer repair

Most sewer smells cost little or nothing to fix: water, cleaning, or a plumber's visit of about $50–$250. A new toilet wax ring runs $50–$200. The big bills are the main sewer pipe. Angi lists $1,100–$4,100 for a repair, and replacing the line runs about $50–$250 a foot. Before you say yes to a big quote, ask three things:

Did you see it on camera? Ask for the video. A camera look is about $125–$500 (HomeGuide), though Angi lists up to $1,725.
Is it a clog or a break? Clearing a clog is about $100–$800. A break means a repair, and that costs much more.
Is it your pipe? A smell at the street or a manhole is the city's to check. Call them first.

Example: about $300 to clear the main line and show you the camera video is in the normal range. A quote to dig up the whole line, with no video, is worth a second opinion.

Ran into a word you don't know?

Sewer smell words, explained

Tap through these before you go looking. The drawings show roughly what each part looks like.

Sewer gas: The smelly air inside drain and sewer pipes. It's mostly hydrogen sulfide. That gas smells like rotten eggs.
Gas meter and gas pipe: Where natural gas comes into the house, and the pipes that carry it to the stove, furnace, water heater or dryer.
Trap (P-trap): The U-shaped bend under a drain. The water it holds blocks sewer gas from coming up.
Floor drain: A round grate in the floor of some basements and laundry rooms. It has a trap too, and it dries out easily.
Pop-up stopper: The plug in a bathroom sink drain. A rod under the sink, held by a nut, moves it up and down.
Overflow hole: The little hole under the rim of a bathroom sink. It's a backup drain, so the sink can't spill over.
Biofilm: The black or gray slime that grows inside drains. It can smell like sewage on its own.
Air valve (air admittance valve): A short plastic stem with a cap, on the drain pipe under some sinks. It lets air in but should keep sewer gas out.
Plumbing vent (vent stack): The pipe that runs from your drains up through the roof. It lets air into the drains and sewer gas out above the house.
Wax ring: The seal between the bottom of the toilet and the drain in the floor.
Tank: The box on the back of the toilet that holds the water for a flush.
Standpipe: The pipe in the wall or floor that the washer's drain hose goes into.
Cleanout (cleanout cap): A short pipe with a screw-on cap, outside or in the basement. It gives a plumber a way into the main sewer pipe.
Main sewer line (lateral): The one big pipe that carries everything from your drains out to the street sewer or a septic tank.
Septic tank and drain field: A buried tank in the yard that holds your home's waste, and the stretch of ground where its water soaks away.
City sewer (manhole): The big sewer pipes under the street, owned by your city. A manhole cover gives workers a way in.
811: The free "call before you dig" number. Someone comes out and marks buried gas, power and water lines.

Still have questions?

Questions people ask most

Is a sewer smell in the house an emergency?

A sewer smell is usually not an emergency, but a strong rotten-egg smell, a smell near a gas appliance, or anyone feeling sick is. Leave the house and call the gas company or 911 from outside (Columbia Gas of Ohio, NW Natural). Sewage coming up out of a drain is urgent too. Stop using water and call a plumber today. A mild smell at one drain can wait a day while you try the water test.

Does sewer gas smell like natural gas?

Yes, sewer gas and natural gas can both smell like rotten eggs. Natural gas has no smell of its own. Gas companies add one so you'll notice a leak (UGI). Sewer gas gets its smell from hydrogen sulfide (ATSDR). If it's strong, near anything that burns gas, or you're not sure, treat it as gas. Get out and call from outside. Many gas companies check for free (Columbia Gas of Ohio).

Is sewer gas dangerous?

Sewer gas in a house is usually a small amount, but it can make you sick, and a lot of it is dangerous. Small amounts over time can cause headaches, sore eyes and tiredness (ATSDR). At high levels you stop smelling it after a few minutes, so a smell that fades isn't proof it's gone (ATSDR, OSHA). Open windows. If anyone feels sick or dizzy, get outside and call for help. Sewer gas can also carry methane, and methane can burn (Mr. Rooter).

Can a sewer smell in the house make you sick?

Yes, breathing sewer gas can give you a headache, an upset stomach or sore eyes. OSHA lists nausea, headaches and watery eyes from breathing low levels over time. Air the house out, find the source, and get outside if anyone feels sick.

Why does my bathroom smell like sewer?

A bathroom usually smells like sewer because a drain dried out, the sink is slimy inside, or the toilet seal is worn. Mr. Rooter, Oatey and Benjamin Franklin Plumbing all name these. Run water in every drain first. Then clean the sink stopper and the overflow hole. If the smell is strongest at the toilet's base, call a plumber about the seal.

Why does my basement smell like sewer?

A basement usually smells like sewer because a floor drain dried out. Pour a bucket of water into it (Roto-Rooter, Oatey). If that doesn't help, check the washer's drain pipe and any capped cleanout pipe. Water coming up out of the floor drain means the main drain is clogged. Call a plumber today.

Why does my sink smell like sewer?

A sink smells like sewer when slime builds up in the drain or overflow hole, or the trap under it is dry. The trap is the water-filled bend under the sink. Once in a while, it's missing. Pull the stopper and clean it. Then clean the overflow hole (Benjamin Franklin Plumbing, Oatey). Kitchen sink? Clean the disposal too. Still smells? A plumber can check the trap and the air valve under the sink (Oatey).

Why does my shower drain smell like sewer?

A shower drain usually smells from slime and hair under the cover, or from a trap that dried out. Traps dry out when a shower isn't used much (This Old House, Bob Vila). Run the shower for a few minutes. Then pull the cover and scrub. If the trap keeps drying out, the pipe may be cracked, so call a plumber (Bob Vila).

Why does the sewer smell come and go?

A sewer smell that comes and goes often means the pipe that lets your drains breathe is blocked. Other drains then pull water out of a trap, and the smell slips in. Wind can push smells back down too (EPA). Gurgling drains are a clue. That vent is on the roof, so call a plumber. Don't climb up there (Angi).

Can a bad wax ring cause a sewer smell?

Yes, a worn wax ring under the toilet can let sewer gas into the bathroom, even with no water on the floor (Mr. Rooter, Oatey). Gently rock the toilet. If it moves, or the smell is strongest at the base, call a plumber. See our guide to a toilet leaking at the base too.

How do I get rid of a sewer smell in my house?

To get rid of a sewer smell, find the drain it's coming from and fix that, because sprays only cover it up. Run water into every drain, clean slimy sink stoppers and overflow holes, and snug any loose cleanout cap (Mr. Rooter, Oatey). If the smell comes back, a plumber can find the source with a camera or by checking the vent.

Who do I call for a sewer smell?

Call a plumber for a sewer smell inside your house. Try the free checks first: the water test, cleaning the sink and its overflow hole, and rocking the toilet. Smell gas or a strong rotten-egg smell? Call the gas company from outside first. On a septic tank? Call a septic service. Smell at the street or a manhole? Call your city's sewer department (LA Sanitation). Renters should call the landlord.

How we built this

The questions follow the order a plumber checks a sewer smell: a gas safety check first, then where the smell is strongest, the tap water, the water test, the drain and toilet up close, and last the main sewer pipe, the septic tank and the street. Each answer makes some causes more likely and others less likely.

Prices are 2026 national averages from published repair-cost guides, rounded. Your local prices will differ.

How we make money: some links go to parts stores that pay us a small commission, and some pro listings pay us when you call them. Verdicts come from the diagnosis, not from who pays more.