When your house smells like sewer, something in the plumbing is letting sewer gas back into the living space. Every drain is designed to keep that gas inside the pipes and send it out through a vent on the roof. When a seal, trap, pipe or vent fails, you smell it. The good news is that the cause is usually one of a handful of things, and some of them take a minute to fix.
Short answer: the most common causes are a dry drain trap, a loose toilet seal, a clogged or damaged vent pipe, a cracked drain line, and a backed-up or broken sewer line. If the smell is like rotten eggs and you also wonder about natural gas, treat it as a possible gas leak first (see below).
Sewer smell or natural gas? Rule this out first
Sewer gas and natural gas can both smell like rotten eggs. Natural gas has an odorant added so leaks can be noticed, while sewer gas contains hydrogen sulfide, which the CDC's ATSDR describes as a gas that smells like rotten eggs and is often called sewer gas.
If the smell is near a gas stove, gas water heater, furnace or gas meter, or you are not sure which one it is, Atmos Energy's advice is to leave the area immediately, then call 911 and the Atmos Energy emergency line at 866-322-8667 from a safe distance. Do not try to find the source yourself. Gas line problems inside the home are covered on our gas line repair in Dallas page.
Common reasons a house smells like sewer
1. A dry P-trap
Every sink, tub, shower and floor drain has a U-shaped bend called a P-trap that holds a little water. That water is the seal that blocks sewer gas. In a guest bathroom, a utility sink or a laundry floor drain that is rarely used, the water can evaporate, especially in a hot Dallas summer. Try this first: run water in every unused drain for 30 seconds.
2. A failing toilet wax ring
The wax ring under the toilet seals the joint to the drain. If the toilet rocks, was recently reset incorrectly, or the wax ring has deteriorated or lost its seal, sewer gas can escape around the base. A smell that is strongest right next to one toilet points here. Our page on toilet repair in Dallas explains the fix.
3. A blocked or damaged vent pipe
Vent pipes run from the drains up through the roof so gas leaves the house and drains flow freely. Leaves, debris or a bird nest can block them, and a vent that was cut or disconnected in the attic can release gas indoors. Gurgling drains together with a smell are a typical sign.
4. A cracked or loose drain line
A drain pipe inside a wall, under a cabinet or beneath the house can crack or separate at a joint. Dallas's clay soil shifts with wet and dry seasons, which puts stress on pipes under slabs and pier and beam homes. A smell in one area with no obvious fixture nearby is a clue.
5. A clogged or broken sewer line
When the main line to the street is blocked or broken, waste backs up and gas has nowhere to go. Slow drains throughout the house, gurgling toilets and sewage coming up in the lowest drain mean the main line needs attention. See sewer line repair in Dallas for what that involves, or drain cleaning in Dallas when the cause is a clog.
Where the smell is tells you a lot
- One bathroom only: check the toilet seal and the trap of any unused sink or shower.
- Laundry room or garage: a dry floor drain or a washer standpipe trap.
- Kitchen: buildup in the sink drain or disposal, or a dry trap on a second sink.
- Several rooms at once: a vent problem or the main sewer line.
- Attic: a vent pipe that is disconnected or ends in the attic instead of the roof.
- Outside near the cleanout: a backed-up or damaged sewer line in the yard.
A North Texas case that shows why this matters
In October 2026, a Tarrant County jury awarded more than $21.6 million to a Fort Worth-area family who said construction defects exposed them to sewer gas and mold. According to Chron and Texas Lawyer, the family's lawsuit said plumbing vents had been directed into the attic instead of outside, and the home became unlivable. Your situation is very likely far simpler, but the case is a reminder that a sewer smell that keeps coming back is a symptom to investigate, not something to cover up.
Warning signs that mean you should call a plumber
- The smell comes back after you refill the traps.
- Several drains are slow, or toilets gurgle when another fixture drains.
- Sewage backs up into a tub, shower or floor drain.
- The smell is in the attic, inside a wall or under the house.
- Anyone in the home has headaches, nausea or eye and throat irritation when the smell is present.
- A pipe split during a freeze (our guide on how to winterize pipes in Dallas explains how to prevent that next time).
A plumber may use a camera inspection of the drain and sewer lines or a smoke test to help identify the source of the odor.
Need a plumber in Dallas?
If your house smells like sewer and the simple fixes have not worked, call now at (877) 340-0703 and describe where the smell is strongest. Calls are answered 24/7. You can also check the Dallas zip codes we serve.
Sources
- Hydrogen Sulfide ToxFAQs (CDC, Agency for Toxic Substances and Disease Registry (ATSDR))
- Recognizing a Leak (Atmos Energy)
- Fort Worth-area family wins $21.6 million after sewer gas, mold lawsuit (Houston Chronicle (Chron))
- Tarrant County Jury Awards $21.6 million to Family Exposed to Sewer Gas in Home (Oct. 14, 2026) (Texas Lawyer (Law.com))
This guide is general information for Dallas homeowners, not a substitute for a plumber inspecting your home.