Odor & Air-Quality Diagnostics · Independent Assessment
Find the Source of the Sewer Smell.
A rotten-egg or sewer-gas odor almost always has a hidden source. Sewer smoke testing pushes a manufactured diagnostic smoke through your drain-waste-vent plumbing and reveals every crack, dry trap, and failed seal where sewer gas is escaping into your building — one diagnostic inside our mystery-odor investigation.
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Diagnostic smoke · We diagnose, we don't do plumbing repair · You own the report
That smell has a source — and it's usually hidden.
You keep catching it: a rotten-egg, sewage, or musty-sour smell that comes and goes near a bathroom, a floor drain, a laundry area, or a basement. You've cleaned, you've plunged, you've poured water down every drain — and it still comes back. The frustrating truth is that sewer-gas odors rarely come from where you smell them. They travel.
Your home's drain-waste-vent (DWV) system is designed to carry sewer gas up and out through the roof while water-filled traps seal it away from your living space. When any part of that system fails — a dried-out trap, a cracked pipe behind a wall, a failed toilet seal, an improperly vented fixture — sewer gas finds a new way in. Because the opening is usually hidden inside a wall, floor, or ceiling, no amount of cleaning at the drain will fix it. You have to find the actual opening.
Guessing is expensive. Opening walls at random, replacing fixtures on a hunch, or re-caulking the wrong seal wastes money and rarely solves it. A smoke test shows you exactly where the gas is escaping — before anyone picks up a tool.
Smoke goes where sewer gas goes.
Sewer smoke testing is a long-established plumbing-diagnostic method. A blower introduces a dense diagnostic testing smoke into the drain-waste-vent system. Because the smoke follows the exact same paths sewer gas would, it escapes wherever there's a defect — and it becomes visible at the opening. What was invisible sewer gas becomes a plume you can point at and photograph.
- Manufactured diagnostic smoke — made specifically for building diagnostics, not a chemical fog and not a fire; your inspector explains the exact product used and can share its safety data sheet on request.
- Follows the plumbing — it fills the same drain and vent network the sewer gas uses, so it exits at every leak.
- Makes the invisible visible — smoke rising from a floor crack, a wall base, a fixture, or a roof vent pinpoints the escape route.
- Whole-system view — a single test can reveal multiple defects at once, including ones no one suspected.
Note: a proper test includes preparation — occupants are advised in advance, traps are addressed, and the method is chosen to suit the property. We'll walk you through what to expect before the visit.
More than a bad smell.
Sewer gas is a mixture of gases produced as waste breaks down — commonly including hydrogen sulfide (the classic rotten-egg odor), methane, ammonia, and carbon dioxide, along with airborne moisture and, at times, biological material. Building codes require the DWV system to keep this mixture sealed away from occupied space for good reason: it is widely recognized as a nuisance and, at sufficient concentrations, a hazard.
There's also a connection to the rest of the indoor-environment work we do. The same hidden gaps that let sewer gas in can carry moisture and bioaerosols into wall and floor cavities — conditions that, over time, support mold growth. Chasing a sewer odor sometimes uncovers a moisture problem, and vice-versa, which is why we run smoke testing alongside thermal imaging and moisture diagnostics rather than in isolation.
If you or others in the building feel unwell, that is a question for a licensed medical provider — we don't diagnose health effects. What we do is find and document the source of the intrusion so it can be corrected.
Where sewer gas gets in.
Dried-out traps
A floor drain, guest bath, or laundry trap that lost its water seal to evaporation — the single most common cause.
Failed toilet seals
A worn or improperly set wax ring letting gas escape around the base of a toilet.
Cracked or broken DWV pipe
A fractured, corroded, or separated drain or vent line hidden inside a wall, floor, or crawl space.
Improper or missing venting
Fixtures plumbed without correct venting, or a vent that's blocked, disconnected, or terminated wrong.
Abandoned / capped lines
Old plumbing from a remodel that was never properly sealed and now leaks gas.
Roof-vent & connection defects
Cracked vent stacks, bad connections, or terminations that pull odor back toward windows and intakes.
One tool inside a full odor investigation.
We don't sell a smoke test as a stand-alone box to check. When you can't find a smell, the answer isn't always the plumbing — so we approach it as a mystery-odor and indoor-air-quality investigation and bring the right diagnostics to bear. Sewer smoke testing is one of them, paired with the tools we already use every day:
- Smoke testing to reveal sewer-gas escape points in the DWV system
- Thermal imaging to spot hidden moisture and temperature anomalies along suspect walls and floors
- Moisture readings to confirm whether an intrusion path is also carrying water
- Air-quality & source assessment when the odor points somewhere other than the drains
We diagnose — you keep the repair independent
We locate and document the problem. We don't perform plumbing repair or remediation. We take no referral fees and we own no plumbing or restoration companies. You get an unbiased report that pinpoints the source — then you hand it to the licensed plumber of your choice.
Your findings are yours to use with whichever contractor, insurer, or attorney you choose. You own the data.
From mystery smell to pinpointed source.
1
Tell us what you're smelling
When it happens, where it's strongest, what's nearby, and any recent plumbing or remodel work. We advise on how to prepare the property for the visit.
2
On-site diagnosis
We run the smoke test through the DWV system and support it with thermal imaging and moisture readings, documenting every escape point we find.
3
You get a clear report
Photographs, locations, and likely origin of each intrusion point — written so a plumber can go straight to the fix instead of exploring.
4
You choose the repair
Hand the report to any licensed plumber you like. No referral, no markup, no stake in who does the work.
When the smell won't quit.
- Homeowners — chasing a recurring sewer or rotten-egg odor no one can locate
- Property managers & landlords — documenting a tenant odor complaint objectively
- Realtors & buyers — running down an odor flagged during a sale before it kills a deal
- Building & facility managers — isolating sewer-gas complaints in commercial space
- Anyone told "it's probably nothing" — who wants the actual source found and documented
Can't find the source of a sewer smell?
Tell us what you're smelling and where — we typically reply within one business day. Independent diagnosis only; no plumbing repair, no remediation, no referral fees, ever.
Educational & informational use. AMOLDBUSTER is an independent indoor environmental health and assessment service — inspection, diagnosis, and consultation only, no plumbing repair, no remediation, no referral fees. Sewer smoke testing documents observed conditions in the drain-waste-vent system and is not a substitute for a licensed plumber's repair scope or a medical opinion on any health effects.
Ownership disclosure. AMOLDBUSTER is a service of Apollo Environmental Solutions and shares common ownership with the Healthy Building Institute of America (HBIA), a credentialing body. AMOLDBUSTER does not perform remediation and does not accept or pay referral fees. HBIA certification does not require the use of AMOLDBUSTER, and HBIA does not evaluate, endorse, or warrant AMOLDBUSTER's work.
© 2026 WeSpiritus — Apollo Environmental Solutions (AMOLDBUSTER). All rights reserved.