Bad Sewer Smell – Finding the Source

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Bad Sewer Smell – Finding the Source

by | Dec 19, 2017 | Plumbing Help, Service Information, Sewer and Drain Cleaning Help

Have you ever came home to a bad sewer smell in your home? You walk in, pause, and your next thought is “what IS that SMELL?”

You may search all over your house and find nothing, but that awful sewer smell has lingered alongside you to every nook and cranny you check.

If you can’t find the source, All Clear Plumbing has knowledgeable plumbers who can figure it out. A sewer smell could indicate a sewage leak. Whether in a slab foundation or a crawlspace, a pinhole or hairline crack in a sewage pipe can often be very hard to find yet cause a big reek.

All Clear Plumbing has a unique technology to handle this issue. We have a machine that creates a dense, non-toxic smoke which we release into your sewer system. We call it a smoke test. Then, we sit back and wait to see smoke.

sewer smell mitigation smoke test

Smoke tests are a secret weapon for plumbers. They aren’t used often but provide an absolutely critical function in our arsenal.
There are a few reasons why we might use a smoke test, but they all come back to the same thing. The sewer is a closed system on purpose, so sewer gases don’t creep into your home. Sewer gases are dangerous and stinky – no one wants even a tiny crack in that system. But there are so many points of failure, from a crack in a pipe inside the wall to a poorly set toilet, to a dry trap. It’s like a needle in a haystack trying to find the source of a leak in the system. We think of the severe cases, like a broken pipe pouring sewage – but the reality is that even a tiny crack can cause issues.

sewer smell smoke test mitigation

Obviously, if there is raw sewage leaking somewhere, that’s typically easy to find. We will go under houses and in crawlspaces to try to find the issue before doing the test.

While the smoke is completely non-toxic and completely safe for humans and pets, it’s very visible. So visible, in fact, that we often have to alert the fire department when we are performing this test. There’s nothing worse than a false alarm scaring the neighbors!

sewer smell smoke test

The smoke is introduced to the system from somewhere like a clean-out. Within seconds, the smoke fills the pipes. You’ll see it coming out of the vent stacks, manholes or drains, but we shouldn’t see smoke anywhere inside the home or building. If the traps, pipes, and seals are doing their job the system – gases can’t exit, so we don’t see any smoke. When we see smoke filtering out through a wall, from the base of a toilet, or from a hidden drain it allows the plumber to find the source of the smell or issue.

This simple, yet incredibly effective tool, gives us a visual cue to the source of your stench, allowing us to narrow in on the problem quickly and with minimal expense.

sewer smell smoke test

Another sign you may have a crack or a poorly sealed drain is sewer gnats in your home. If see tiny, black bugs flying around your home, the unmistakable smell may be looming.

Do-it-yourselfers may want to try this method before calling All Clear Plumbing. Find any unused drain and pour five gallons of water in it. That will fill the trap and could stop a sewer smell that’s emanating from a dry trap.

If your problem – and smell – still lingers, All Clear Plumbing has a staff of expert plumbers and talented apprentices who are well versed in the art of smoke testing. We are some of the best in the Upstate when it comes to plumbing repairs and is often who gets called in when everyone else gets stumped. Don’t live with a rotten egg smell in your house or sewer flies invading your space! We can root out the cause and address the problem immediately, in many cases. If you’d like to discuss your plumbing issue with us, call 864-979-7059 between 7:30 am and 5 pm, Monday through Friday. We are available for emergencies 24/7/365.

Article Author: Anja Smith

Managing Partner

Anja Smith is the author behind the All Clear Plumbing blog. She also writes regularly for Plumber Magazine,, and on Medium