Why Does My House Smell Like Sewage? Common Causes and How to Fix It

Published September 2, 2026 · Snake-It-Away Inc.

A sewage smell inside your home almost always means one thing: gas that is supposed to stay sealed inside your pipes is finding a way out. Usually it is something small and fixable, like a dried-out drain. Sometimes it is a warning sign from your sewer line. Here is how to tell the difference.

What that smell actually is

Your plumbing is built to keep sewer gas out of your living space. Every drain has a curved section of pipe called a trap that holds a little water, and that water forms a seal that blocks gas from coming back up. Vent pipes running up through your roof let the system breathe so the traps stay full. When you smell sewage, one of those defenses has failed. The job is figuring out which one.

The most common causes

• A dried-out drain trap. This is the number one cause and the easiest to fix. A drain you rarely use, like a basement floor drain, a guest bathroom, or a laundry sink, can have the water in its trap slowly evaporate. Once that water is gone, nothing is stopping the gas.
• A blocked vent pipe. Leaves, a nest, or debris can plug the vent on your roof. Without it, drains gurgle and gas gets pushed back into the house instead of out the top.
• A clog building up. A partial blockage traps waste that sits and gives off gas. If the smell comes with slow drains, this is a likely cause.
• A cracked or broken sewer line. Roots, age, or a shifted pipe can break the line underground, and the smell can seep up through the lowest drains. Tree roots are one of the most common reasons a line cracks in older Boston-area homes.
• A failed seal under a toilet. If the smell is strongest right around one toilet, the wax ring underneath it may have failed.

What to try first

Start with the free fixes. Run water in every sink, tub, shower, and floor drain for a minute, including the ones you never use, to refill any dried-out traps. Pour a couple of cups of water into basement and laundry drains that sit unused. If the smell fades over the next day and stays gone, a dry trap was your answer.

When to call us

Call when the smell keeps coming back, shows up at more than one drain, or comes with gurgling sounds and slow drains. Those point to a venting problem or a blockage deeper in the main line, not a simple dry trap. And if you ever see sewage backing up into a tub, sink, or floor drain, treat it as an emergency. Here is what to do the moment a main line backs up, and our 24/7 emergency service can get someone out fast.

How we find the source

When the cause is not obvious, we do not guess. A camera inspection sends a waterproof camera down the line so we can see exactly where the problem is, whether it is a break, roots, or years of buildup. If the line is coated and clogging up, hydro jetting clears it out completely. You see what we see on the screen, and you only pay to fix what is actually wrong.

Get the smell gone for good

A sewage smell is your home telling you something. Sometimes it is a two-minute fix, sometimes it needs a pro. Either way, we can help you figure out which. Call Snake It Away at (781) 858-8314. Family-owned since 1997, serving homes across the Boston metro.