Sewer Smell or Backup
A sewer smell in the bathroom, water coming up around a toilet, or a downstairs drain that fills when someone runs water upstairs. Here is what causes each in Tacoma homes, what you can safely check, and how we fix it so it stays fixed.
Why Does My House Smell Like Sewer?
Sewer gas is getting out where the drain system should be sealed: a trap that has dried out, a toilet seal that failed or was never set on a flange, a cracked drain or vent pipe, or a sewer line that is backing up. If water also rises at the lowest drain, the line itself is blocked.
The backup we point to was in Fern Hill, in Tacoma’s South End, at the start of September, when the main sewer line of a house had backed up. James opened the cleanout in the front yard and cabled the line until it cleared, and what came back on the cable explained the clog: roots, pulled out of the old concrete sewer pipe. The camera showed how they had gotten in, through a newer section of SDR35 pipe that was broken where it joined the concrete. With the house draining again, James wrote up the options: jetting from the outside cleanout, a maintenance plan to keep the roots out, and an excavated repair of the broken joint.
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What Causes a Sewer Smell or Backup
The causes we find in Tacoma homes, roughly in the order we check them.
A Dry Trap
Every drain has a trap that holds a plug of water to keep sewer gas in the pipe. In a guest bath, a basement floor drain or a shower nobody uses, that water evaporates and the smell comes straight up. A minute of running water refills it.
A Toilet Seal That Failed, or Was Never There
In Tacoma’s West End this September, water came out from under a downstairs toilet whenever the house used water. James pulled the toilet, cabled the sewer several times and put a camera down it, and the line had no blockage, only a groove worn into the old concrete pipe by decades of water. The real problem was under the toilet: there was no closet flange, just wax rings sitting on the floor around the drain. He reset the toilet on a new wax ring and wrote up an estimate to install a proper flange.
Roots in the Sewer Line
Roots find the moisture in a sewer line, get in through a crack or a loose joint, and grow into a net that catches everything. The Fern Hill line above is the textbook case: concrete pipe, a broken joint and a cable full of roots.
A Broken or Offset Joint
A joint that has cracked or shifted lets roots in and lets sewage and sewer gas out, into the soil, the crawl space or the yard. It is why a cleaned line backs up again, and the repair is to the joint, not another cleaning.
A Vent That Is Blocked or Cracked
Plumbing vents carry sewer gas out through the roof and let drains breathe. A vent blocked by debris lets traps siphon dry, and a cracked vent pipe inside a wall or attic lets the smell into the house with no water in sight.
A Full Septic Tank
On Tacoma’s unincorporated south side some homes are still on septic. A tank that is full, or an outlet that is clogged, backs up at the lowest drain first, and the smell often shows up outside near the tank lids before it reaches the house.
Where you smell it tells you a lot. One room usually means that room’s trap or toilet; the whole house and the outside point at the main line or a vent; the crawl space points at a broken drain or side sewer under the house. In Tacoma the side sewer is the homeowner’s all the way to the City main, so that last case is yours to fix.
What You Can Safely Check
Ten minutes and a flashlight. Nothing that is full of sewage gets opened.
Refill the Quiet Drains
Run water for a minute in every sink, tub and shower that rarely gets used, and pour a bucket into a basement floor drain. If the smell fades within the hour, a dry trap was the cause.
Watch the Lowest Drain
Run water upstairs or flush a toilet while someone watches the lowest drain in the house. If water rises there, stop using water, because the blockage is past every fixture.
Notice Whether Anyone Is Using Water
If sewage comes up in a Tacoma home while nobody is running any water, the problem may be in the City’s main, and the City of Tacoma asks you to call its 24-hour wastewater line right away.
Look at the Toilet Base
A toilet that rocks, water at the base, or a smell right at the floor points at the seal under the toilet, not the sewer line.
When to Stop
Stop if sewage is coming up any drain, and do not open a cleanout cap on a line that is backed up, because the water behind it comes out with it. Skip chemical cleaners on a backup, and tell us if you have already used one. The drain clog or sewer line guide walks through what each pattern usually means.
How We Fix a Sewer Smell or Backup
The fix follows the cause, and nothing gets dug up until we know what failed.
Clear the Line From the Cleanout
We open the main line at the cleanout or, where there is none, at the lowest toilet, and run the cable until the house drains at full speed.
Learn more →Camera the Line Before Any Digging
The camera shows roots, breaks, offsets and old pipe, so a repair is priced on what is actually in the ground.
Learn more →Reset or Rebuild the Toilet Seal
A failed wax ring gets replaced, and a toilet with no closet flange gets one, so the seal has something solid to sit on.
Learn more →Repair the Joint or Replace the Line
A broken joint is a spot repair, and Orangeburg or a line broken in several places is a replacement, with the permit pulled for your address.
Learn more →Urgent Calls During Business Hours
A backup in progress goes to the front of the schedule during our Monday to Friday hours, with same-day service when the schedule allows. Until we get there, keep water out of the drains.
Learn more →Repairs, permits and cleanouts are on our sewer line repair page, or browse all common problems.
Why Tacoma Homeowners Call Royal Flush
Veteran-Owned & Local
Family-operated out of Tacoma, serving Pierce and King County.
Upfront Pricing
You approve a clear price before any work starts. Estimates are free.
Licensed & Insured
Washington license #ROYALFP787R1, bonded and fully insured.
Fast Local Response
Same-day service when the schedule allows during business hours.
Flexible Payments Through Wisetack
Spread a larger repair over monthly payments, with no prepayment penalties and no hidden fees. VIP Home Protection members save 10% on every service.
Sewer Smell and Backup Questions
Straight answers before you pick up the phone.
In the small amounts that cause a household smell, sewer gas is mostly an irritant, but it carries hydrogen sulfide and methane, and it is never something to live with. Air the room out, refill any dry traps, and if the smell stays, have the source found rather than covered up with a candle or a spray.
Because a pipe under it is leaking. A cracked house drain under the floor, a broken side sewer in the yard, or on septic a full tank or a failing drainfield all let sewage and its smell into the soil. A camera run from a cleanout finds the break, and the repair goes to that section of pipe.
Don’t Gamble On Your Plumbing!
Veteran-owned, licensed and local. Call us or [request service](/quote) about a sewer smell or a backup anywhere in Tacoma and the South Sound, and we will say what we found before any work starts.