Smoke Test for Drains: The Fastest Way to Detect Odors and Plumbing Issues
Sewer odors in a home or building usually come from a hidden problem somewhere inside the drainage or ventilation system. A smoke test is one of the most reliable techniques to locate the exact source of the issue — whether it’s a crack in a pipe, a dried trap, a blocked vent, a loose connection, or an air leak behind a wall.
At Drain 5 Étoiles, we use professional-grade smoke generators that make defects visible quickly and without causing damage to your property.
What Is a Smoke Test for Drains?
A smoke test involves injecting a non-toxic, residue-free smoke into the plumbing or drainage system.
If smoke escapes from an area where it should never appear, that location is where the problem is.
A smoke test can reveal:
- cracks or holes in pipes
- loose or poorly sealed joints
- blocked or malfunctioning vent pipes
- dried or defective traps
- improper installations
- water infiltration points
This method gives clear, visual results within minutes and helps avoid guesswork.
Why Choose a Smoke Test?
Instantly pinpoint the source of sewer odors
Odors can travel through walls, ceilings, floors, and ventilation. Smoke shows exactly where the leak or defect is, instead of relying on trial and error.
Ideal for homes, condos, rental units, and commercial buildings
Smoke testing helps:
- avoid opening walls or ceilings unnecessarily
- confirm plumbing conditions before renovations
- diagnose repeated odor complaints from tenants or owners
- verify the quality of previous plumbing work
100% safe and chemical-free
The smoke we use is:
- non-toxic
- non-flammable
- odorless
- safe for pets and people
- approved for use in plumbing diagnostics
Once the test is complete, the smoke dissipates quickly and does not leave stains or residue.
Issues Detected by a Smoke Test
Hidden pipe leaks behind walls or ceilings
Even hairline cracks can allow smoke to escape. A smoke test can reveal leaks that are impossible to see from the outside.
Venting problems (roof vents, blocked stacks)
Improper ventilation often causes slow drainage, gurgling sounds, or recurring sewer smells. If a vent is blocked or disconnected, smoke will expose the problem.
Dried or improperly installed P-traps
A common cause of basement and bathroom odors is a dried or poorly installed trap. Smoke will immediately show if sewer gases are bypassing the trap.
Faulty connections or unsealed fittings
Loose or unsealed fittings can be hidden inside walls or ceilings. When smoke appears where it should not, we know exactly where the defect is.
How a Smoke Test Works (Step by Step)
1. Initial Assessment
We start with a short discussion and visual inspection to understand:
- Where the odors are strongest
- When they occur (all the time, after rain, in cold weather, etc.)
- Which rooms or fixtures are affected
This helps us select the right access point and test strategy.
2. Installation of the Smoke Generation System
We connect our smoke machine to the appropriate drainage or vent access point.
This might be:
- a clean-out
- a floor drain
- a roof vent
- another accessible part of the system
3. Filling the System With Smoke
The system is gently pressurized to push smoke throughout the pipes, drains, and vents.
We control the pressure to protect the system and ensure smoke reaches all the necessary areas.
4. Inspection and Observation
Our technicians walk through the property, inside and sometimes outside, to detect visible smoke around:
- bathrooms and powder rooms
- kitchens
- floor drains and laundry rooms
- basement plumbing and mechanical rooms
- roof vents (if accessible)
- walls or ceilings, when there are openings or visible gaps
Where smoke appears, there is a path for sewer gases or air leaks — and often the source of your odor problem.
5. Complete Diagnosis and Recommendations
Once the test is complete, we identify:
- the exact source or sources of the problem
- the type of defect (leak, crack, missing trap, vent issue, etc.)
- the areas that should be repaired
We then provide clear recommendations and, if you wish, can coordinate or perform the necessary plumbing work.
Why Choose Drain 5 Étoiles?
Drain and sewer specialists
We focus on drainage systems every day, which allows us to be extremely precise when diagnosing sewer and odor problems. This experience helps reduce guesswork and wasted time on site.
Fast service
We serve:
- Montreal
- Laval
- the West Island
- the North Shore
- the South Shore
and surrounding areas, with flexible scheduling options depending on urgency and accessibility.
Professional-grade equipment
Our smoke testing machines are designed specifically for plumbing and drainage diagnostics. They offer consistent smoke output, controlled pressure, and reliable results.
Trusted by property managers and building owners
We regularly work with:
- condo boards and syndicates
- multi-unit residential buildings
- rental properties
- commercial and mixed-use buildings
- real estate investors and managers
Our goal is always the same: clear, documented findings that help you make the right repair decisions.
When Should You Consider a Smoke Test?
You should consider a smoke test if you notice:
- a persistent sewer smell that comes and goes
- an odor coming from the kitchen, bathroom, or basement
- gurgling noises in the plumbing when you use certain fixtures
- a stronger smell after heavy rain or high humidity
- odors near a floor drain or mechanical room
- unexplained complaints from tenants or family members
- doubts about the quality of work done by a previous contractor
Sewer odors do not disappear on their own. They always point to a defect or a weak point in the system. A smoke test allows you to see what is happening behind the walls.
Frequently Asked Questions About Smoke Testing for Drains
What is a smoke test for drains?
A smoke test for drains is a diagnostic procedure where non-toxic smoke is introduced into the plumbing or drainage system. If there is a leak, crack, missing trap, or venting problem, smoke will escape through the defect, making it easier to identify the exact location of the issue.
Is the smoke safe for people and pets?
Yes. The smoke we use is specifically designed for plumbing diagnostics. It is non-toxic, non-flammable, and does not contain harsh chemicals. It dissipates quickly after the test and does not leave stains or residue on surfaces.
Do I need to leave the house during the test?
In most cases, you can stay in the house while we perform the test. Some clients prefer to step outside for part of the process because seeing smoke inside the building can be surprising, even though it is safe. If anyone in the home has respiratory sensitivities, we can adapt our approach or schedule the test when it is more comfortable for everyone.
How long does a smoke test usually take?
For a typical residential property, a smoke test usually takes between one and two hours, depending on the size of the building, the access points, and the complexity of the plumbing system. Larger multi-unit or commercial buildings may require more time.
Will a smoke test damage my plumbing or my house?
No. The test is performed at a controlled, low pressure that is safe for your plumbing system. The smoke itself does not damage pipes, fixtures, paint, or finishes. If smoke appears inside the home, it is because there is a path that sewer gases are already using — the test simply reveals it.
What should I do to prepare for a smoke test?
In most cases, you do not need to do much. It can help to:
- ensure we have clear access to the basement, mechanical room, and key plumbing areas
- let us know if there are any known open drains or disconnected pipes
- inform tenants or other occupants that a test with smoke will be performed
We will give you simple instructions before the appointment if any specific preparation is needed.
How much does a smoke test cost?
The cost depends on the type of building, the number of systems to test, and the complexity of the layout. Once we know a bit more about your situation (location, type of property, symptoms), we can provide a detailed estimate before scheduling the work.
Can a smoke test find every plumbing problem?
A smoke test is extremely effective at finding paths where air and sewer gases can escape. It is ideal for locating odors, venting problems, and many types of leaks. For other issues, such as blockages or structural problems inside the pipes, we may recommend combining the smoke test with a drain camera inspection for a complete diagnosis.
Is a smoke test useful for property managers and investors?
Yes. For multi-unit buildings, recurring odor complaints can be difficult to resolve. A smoke test gives a visual and objective way to document defects, plan repairs, and avoid repeated interventions that do not address the root cause of the problem.
