Sewer Smell in House: Wax Ring Fix $50 to $200 (Angi 2026)

National figures. Most sewer smells come from a dry trap, a toilet seal or a vent; a cracked line costs more and is priced on the sewer pages linked below.

Is it urgent? When a sewer smell is a danger

Rotten egg can be natural gas, not sewer gas. Connecticut's utility regulator says natural gas has no odor of its own and gas companies add mercaptan to give it that rotten egg smell, so treat a strong or uncertain smell as gas first.

• Leave now, then call: a strong rotten egg smell, or any chance it is gas. Go outside without touching light switches, doorbells or thermostats (Connecticut PURA), and call 911 or the gas utility's emergency number from outside; National Grid says to stay out until the utility says it is safe. More on a gas smell in the house.
• Get fresh air now: dizziness, nausea, headache or drowsiness, which the Virginia Department of Health lists for high sewer gas levels. Open windows and step outside.
• Call now: sewage coming up a drain. See sewage cleanup, or septic backup if the house is on a tank.
• This week: a smell that comes back after you refill the traps, or drains that gurgle as well (see toilet gurgling).
• Can wait: a faint smell from a guest bathroom no one uses. Master plumber Chuck Pound told Bob Vila a sink trap can dry out in under 30 days. Run the water for a minute.

Sewer smell in the bathroom: traps, wax rings and vents

The cheapest fix is a dry trap, and the most common paid one is a toilet wax ring at $50 to $200 in Angi's July 2026 guide. HomeGuide's toilet guide is blunt about it: if you suddenly start smelling sewage, it's a good bet the wax ring cracked.

• Dry trap. Angi says a P-trap holds water as an airtight seal against the sewer, and the seal is lost to evaporation, a leak or siphoning. A sink, tub or shower that sits unused is the usual suspect.
• Toilet seal. Angi's sewer gas guide lists a loose or worn wax ring and gaps at the toilet base, and Family Handyman lists a leaky wax ring among basement causes too.
• Old S-trap. Angi says S-traps no longer meet plumbing code, and that poor venting can pull the water out of a trap.
• Vent. Bob Vila's master plumber lists broken or clogged vent pipes, along with a sewer line backup and a full septic tank.

Three wax ring figures from two publishers; they differ by guide and year, so all three are shown.

Sewer smell in the basement: floor drains and cleanout plugs

A basement sewer smell is most often a dry floor drain, and the fix costs nothing. Family Handyman ranks the causes in order of probability, and the Virginia Department of Health adds that sewer gases collect in low areas such as basements.

1. A dry trap under a floor drain, laundry tub or basin. Pour in water, then a little cooking oil; Family Handyman says the oil sits on top and slows evaporation.
2. A missing cleanout plug inside the floor drain, which Family Handyman calls a direct path for sewer gas around the water trap.
3. A dry toilet trap in a basement bathroom no one uses.
4. A leaky wax ring on that toilet.
5. A cracked or broken sewer line. This one needs a camera; a sewer camera inspection costs $125 to $500 in HomeGuide's guide.

A smell that arrives with a wet floor drain is a backup, not a trap; see basement flooding.

Sewer gas smell in the house: symptoms and health effects

At low levels sewer gas is mostly a nuisance odor, the Virginia Department of Health says, but long exposure at around 10 ppm or less can cause eye irritation, headache and fatigue (ATSDR). The two federal agencies give different thresholds, so both are shown.

Parts per million in air. OSHA lists the long-exposure symptoms at 2 to 5 ppm as nausea, tearing eyes, headaches or loss of sleep.

• Your nose is not a meter. ATSDR says people lose the ability to smell the gas after 2 to 15 minutes at about 100 ppm, so a smell that fades can mean more gas, not less.
• Deadly levels are not expected at home. The Illinois Department of Public Health says very high levels can kill within a few breaths but would not be expected in a house, and that people smell it well below levels that cause harm.
• It can burn. The Virginia Department of Health says methane is explosive and hydrogen sulfide is flammable, and to avoid smoking, electrical appliances and sparks near sewer gas. OSHA puts hydrogen sulfide's explosive range at 4.3 to 45 percent in air.

Sewer gas or a natural gas leak? How to tell, and when to leave

You cannot reliably tell them apart by nose: both read as rotten eggs, and the Virginia Department of Health says that smell can come from a gas leak, so go outside and call the fire department. Connecticut PURA says gas companies stop leaks at no charge. If the smell clearly comes from one drain and stops once you run water into it, a dry trap is the likely cause, since the Virginia and Illinois health departments both name dry traps; if you cannot place it, treat it as gas.

Plumbing vent clogs: gurgling plus a sewer smell

A clogged plumbing vent costs $100 to $200 to clear in HomeGuide's guide, or $150 to $200 in Angi's, more for a bad blockage. Angi lists slow drains, gurgling and sewer odors as the signs, because gases build up and leak into the living space. The EPA adds that a blocked or frozen roof vent can cause an odor.

If clearing the vent does not stop the gurgle, the main line may be the problem: HomeGuide puts main line snaking at $150 to $500 and cites Roto-Rooter at $500 to $900 to hydro jet a main sewer drain. Prices for each are on drain cleaning.

Sewage smell outside the house: septic tank, drain field or sewer line

On a septic system, the EPA lists sewage odors around the septic tank or drainfield as a failure sign, along with backups, gurgling, damp spots and spongy soil over the field.

• Smell at the tank. Start with septic tank pumping, and never lean into or enter a septic tank; Purdue Extension warns tanks can generate hydrogen sulfide and methane.
• Wet, spongy or smelly ground over the field. That is a drain field repair question.
• Smell near the roof. The EPA says a blocked or frozen roof vent can cause the odor; the vent costs above apply.
• On city sewer. A smell in the yard over the line points to a crack; see sewer line repair and trenchless sewer line replacement for what each fix costs.

Well water that smells like sewage or rotten eggs

A rotten egg smell in well water is usually hydrogen sulfide, which the Florida Department of Health says can occur naturally in groundwater and is made by sulfur bacteria that are not harmful. A sewage smell is different: test the water.

• Test first. Florida, Oregon State and Colorado State all say to test for coliform bacteria at least once a year, and Oregon State adds whenever taste or color changes. Colorado State says coliforms suggest disease-causing agents may be in the water. See well water testing.
• Septic nearby? The EPA lists high nitrate or coliform in drinking water wells as a sign of septic failure, and Colorado State says to test more often if the septic system has malfunctioned.
• Hot water only. University of Nebraska Extension says to consider replacing the water heater's magnesium rod; see water heater repair.
• Treatment. Nebraska lists activated carbon, oxidizing filters and de-aeration, and the University of Georgia calls shock chlorination the most common way to sanitize a well. Options and prices are on well water treatment.

How a plumber finds a sewer smell, and what the visit costs

A plumber's service call runs $100 to $250 in Angi's March 2026 cost table, and its summary says $150 to $250. HomeGuide lists a diagnostic fee of $50 to $90 that is often deducted if you hire the pro.

• Hourly: $45 to $200 (Angi) or $45 to $150 (HomeGuide).
• Distance: Angi lists a $50 to $300 trip fee beyond 10 miles.
• Smoke test: none of the cost guides we checked (HomeGuide, Angi, HomeAdvisor) prices one, so ask for the price before it is run.
• Camera: for a suspected crack under the slab or yard; prices are on sewer camera inspection.

Questions to ask the plumber about a sewer smell

• What is the visit fee, and is it credited to the repair?
• Which fixture or fitting is it, and how do you know? A trap, seal or vent should be shown to you.
• Is a camera or smoke test needed, and at what price?
• License number and proof of insurance. Ask for both yourself; the plumbing license table shows who licenses plumbers in six states.

Do this now: track down a sewer smell

1. Rule out gas. If there is any chance it is natural gas, stop and leave (see the urgent section above).
2. Run water in every drain. Sinks, tubs, showers, floor drains and the laundry tub, especially ones no one uses.
3. Add oil to floor drains. A little cooking oil on the water slows evaporation (Family Handyman).
4. Check the floor drain cleanout plug and any cleanout caps; Angi lists loose caps as a cause.
5. Look at each toilet base. Angi lists gaps at the base and a worn wax ring as causes.
6. Listen for gurgling. Angi lists gurgling plus sewer odor as a clogged vent sign.
7. Call the plumber line if the smell is still there a day later.

Plumbing prices in general are on how much a plumber costs. Calls go to an independent company that serves your area and takes this kind of job; hours vary. How calls work.