Why Your House Smells Like Sewer and How to Stop It

Start by Following Your Nose

Before you buy anything, walk the house and notice two things. Where is the smell strongest, and when does it show up? The answers narrow it down fast.

• One bathroom or one drain. Usually a dry drain, the seal under the toilet or a problem with that room's pipes.
• The whole house, or it comes and goes. Think vents, a partial clog in the main line or a cracked pipe.
• Only when the AC runs. The air system is pulling the smell in from somewhere else.
• Outside, near the house or the street. A vent on the roof, a cleanout, a septic tank or a City sewer line.

Timing helps too. A smell after the house sat empty points to dry drains. A smell right after a flush points to the vents or the toilet. A smell with slow drains or gurgling points to a clog.

A Drain That Dried Out

Every drain has a U-shaped bend under it called a trap. It holds a little water, and that water is the only thing stopping sewer gas from coming up the pipe. When a drain goes unused, the water slowly evaporates, and the smell walks right in. In a hot South Georgia summer, that happens faster than most people expect.

The usual suspects are a guest bathroom nobody uses, a spare tub or shower, the floor drain in a laundry room or garage, and the pipe behind the washing machine.

• Run every sink, tub and shower for about a minute, and flush every toilet.
• Pour a big pitcher of water into each floor drain and down the washer's drain pipe.
• For a drain you rarely use, a spoonful of cooking or mineral oil on top of the water slows the drying.
• Open a window, then come back in an hour. If the smell is fading, you found it.

If one drain keeps smelling even with water in it, the trouble is more likely slime inside that drain, and the fix is cleaning out the smelly drain itself.

This happens a lot in houses left empty for a summer. Owners closing up rentals around Brookwood and North Patterson between leases run into it every year. A neighbor running the water now and then keeps it from happening.

The Seal Under the Toilet

A toilet sits on a ring of wax that seals it to the drain pipe in the floor. When that ring fails, it can leak sewer gas without leaking a drop of water, so nothing looks wrong. Plumbers say this is one of the most common causes of a smell in one bathroom.

• The smell is strongest at the base of the toilet.
• The toilet rocks or shifts when you sit on it. Wax only seals once, so any movement opens it up.
• The floor around the base is stained, soft or damp.
• New flooring went in, and the toilet now sits higher than the pipe below it.

Fixing it means pulling the toilet and setting it on a new seal, and sometimes repairing the flange it bolts to. Plumbers handle this all the time during a toilet repair, and they can check the floor underneath while the toilet is off.

Vents and Drains That Get Sucked Dry

The pipes sticking up through your roof are plumbing vents. They let air into the drain pipes so water flows smoothly. When a vent is blocked by leaves, a bird's nest or a critter, a flush or a draining tub pulls air from the only other place it can, which is the traps in your drains. The water gets sucked out, and the smell gets in.

Signs of a vent problem are gurgling in a sink or tub when the toilet flushes, a smell right after heavy water use, and drains that run slower than they should. If the toilet itself is doing the gurgling, this guide to a gurgling toilet walks through every cause.

A bathroom remodel can cause the same trouble. A drain installed without a trap, an S-shaped trap that siphons itself dry, an under-sink air valve that stuck open or an old pipe left uncapped inside a wall will all let gas through. Georgia's plumbing code doesn't allow S-shaped traps for exactly this reason. If the smell started right after work in one room, look at what changed there first.

Getting on a roof isn't worth the risk for most people. A plumber can clear a vent and run a smoke test, which pumps harmless smoke into the drain pipes so it shows exactly where the gas is escaping.

A Clog or a Cracked Pipe

If water in the drain traps isn't the issue, the smell may be coming from the pipes themselves.

• A partial clog in the main line. Waste sits in the pipe instead of flowing away. You may notice slow drains, gurgling and a smell strongest at the lowest drain in the house. Drain cleaning clears it, and roots usually mean it will come back.
• A cracked pipe. Older homes often have cast iron or clay drain pipes that crack with age or get broken by tree roots. A crack under the floor or in a crawl space lets gas out where you can't see it. A sewer camera inspection shows the damage before anyone digs, and sewer line repair in Valdosta fixes the broken section.

If dirty water rises in a tub, a shower or a floor drain, stop using water in the house right away. That's a backup, and it needs a plumber now, not tomorrow.

When the Smell Comes Out of the AC Vents

In Valdosta, the AC runs most of the year, and it can spread a smell to every room. The air system pulls air from wherever it leaks in, so a smell from a duct doesn't mean the problem is in the duct.

• A dry drain or a leaking pipe near the return vent, the big grille the AC pulls air through.
• Leaky ducts in a crawl space or attic pulling in air from around a broken pipe.
• A fresh-air intake on the roof sitting too close to a plumbing vent.
• The AC's condensate drain tied into a house drain the wrong way.

Refill every trap first. If the smell only shows up with the AC on, a plumber can check the pipes, and an AC tech can check the ducts and the drain line.

On a Septic Tank

Plenty of homes with a Valdosta address aren't on City sewer and use a septic tank instead. A whiff near the roof vent after a lot of water use can be normal. A smell inside the house, slow drains everywhere, or a soggy, smelly patch over the drainfield is not.

Those usually mean the tank is full or the drainfield isn't taking water. Don't pour additives or bleach in hoping to fix it. Have the tank pumped and checked with septic tank service, and ask what they see at the outlet and the drainfield.

Is Sewer Gas Dangerous?

In most homes, it's far more nasty than dangerous. Still, a strong smell that won't go away isn't something to live with. If anyone gets a headache, feels sick or gets dizzy, open the windows, get outside and get help if it doesn't pass.

If the smell is strongest outside near the street or a manhole and your home is on City sewer, it may be the City's line, and City of Valdosta Utilities is the place to tell.

Smells That Need a Plumber

Refilling the drains costs nothing and takes ten minutes. If that doesn't do it, it's time to call when any of these is true.

• The smell is still there a day after every drain has water in it.
• The toilet rocks, or the floor around it is soft or stained.
• Sinks or tubs gurgle when the toilet flushes.
• Several drains are slow, or sewage comes up in a tub or floor drain.
• The smell started right after plumbing or remodeling work.
• You're on septic and the drains are slow or the yard is wet and smelly.