Published by American Structural Pest Control West | Serving the South Bay, CA

Most people have never heard of a plumbing smoke test in the context of pest control. Honestly until a couple of years ago neither had we. But a case that pushed our team to think beyond the traditional boundaries of what pest control looks like changed that completely and it’s the reason we now offer this service to our customers.

This article tells that story, explains what a plumbing smoke test is, how it connects to rodent entry and why it might be the missing piece for homeowners dealing with a persistent rodent problem that conventional methods haven’t been able to fully resolve.

The Case That Changed Everything

About two summers ago one of our technicians responded to a call from a long-term customer dealing with a severe and ongoing rodent problem. We’re talking three to six months of continuous activity in a home where the customer had been with us for years and trusted our team completely. That trust meant everything to us and resolving this was personal.

We started where we always start: a thorough inspection and full evaluation of the structure. Our team identified every visible entry point and completed all necessary exclusion repairs. Gaps were sealed, vents were addressed and everything that should have closed off access to the home was done. And yet the activity continued.

We installed game cameras in the attic to monitor what was happening. What we saw was striking. Traps were catching four to six rats within short periods of time. But within just a few weeks of each round of trapping the problem would return in full force. We conducted multiple re-evaluations, additional inspections and team brainstorming sessions. Something was still allowing rodents to get in and we couldn’t find it through conventional means.

That’s when we made a decision. We had to dig deeper and step outside of the traditional pest control realm. The team suggested a smoke test, a method most commonly performed by plumbing companies, not pest control technicians. It wasn’t an easy path. Finding a plumbing company willing to partner with us on something this unconventional took numerous calls and several declined requests. But our customer connected with a company willing to step in and we moved forward.

What the Smoke Test Revealed

On the day of the smoke test our CEO was on-site to observe, ask questions and learn directly from the plumbing professionals. We didn’t just want answers. We wanted knowledge and understanding so our team could carry this capability forward and offer it to other customers facing similar situations.

The test revealed something that explained everything. At some point prior to our involvement, renovations had been done to a restroom in the home and they weren’t exactly up to code. During the remodel a toilet had been relocated. Instead of properly capping the old vent and installing a new one the vent was rerouted incorrectly. The toilet vent was discharging directly into the attic space rather than extending above the roofline as required.

This created a direct breach between the sewer system and the attic. Rodents were traveling up through the plumbing and entering the structure through that improperly vented opening.

The game camera footage suddenly clicked into place in a whole new way. The cameras had consistently captured rodent activity between 2am and 3am, hours that had seemed significant but unexplained. By that point in the night the home’s plumbing system had largely drained. Dishes were done, showers were finished, toilet use had stopped. The pipes were quiet and the conditions were perfect for rodents to travel through the system undetected and emerge into the attic.

Once the source was identified the solution was straightforward. ASPCW properly rerouted and corrected the venting issue. Rodent activity was resolved within two weeks. We’re proud to say that nearly two years later that customer continues to live rodent-free.

What Makes Rodents Such Capable Plumbing Travelers

If the idea of rats moving through your plumbing sounds far-fetched, the biology tells a different story. Rats are remarkably capable swimmers. They can hold their breath for up to three minutes and tread water for up to 72 hours continuously. That three-minute breath hold is more than enough time to navigate the U-bend of a toilet or travel through a flooded section of pipe and emerge somewhere inside your home.

Their collapsible rib cages, which we mentioned in our article on signs of a rodent problem, also make them extraordinarily capable of squeezing through tight bends and narrow passages within a plumbing system. A rat that finds an opening connected to the sewer line has both the physical capability and the persistence to follow it wherever it leads.

This is worth understanding in the context of the South Bay specifically. Many homes in our area that have not had major renovations are working with plumbing systems that are over 50 years old. Pipes of that age can develop cracks, separations at joints, deteriorated seals and failed connections that create exactly the kind of breaches rodents can exploit. A home that looks completely sealed from the outside may have vulnerabilities running through its plumbing that have never been identified.

What Is a Plumbing Smoke Test?

A smoke test is a diagnostic method used to detect leaks, cracks, broken joints or faulty connections within sewer pipes, vents and drain lines. Non-toxic artificial smoke is forced into the plumbing system under gentle pressure and technicians then observe where smoke emerges from points it shouldn’t. Any location where smoke appears indicates a breach in the system, whether that’s a cracked pipe, a failed joint, an improperly connected vent or an opening that shouldn’t be there.

The smoke used is completely non-toxic and dissipates quickly. It leaves no residue and poses no risk to people, pets or the structure. It is specifically designed for diagnostic use in occupied residential and commercial buildings.

Smoke tests have long been a standard diagnostic tool in the plumbing industry for identifying sewer gas leaks and code violations. The connection to pest control, specifically to rodent entry through compromised plumbing, is a newer application and one that most pest control companies have not yet explored.

How ASPCW Performs Smoke Tests

After the case that introduced us to smoke testing our CEO made it a priority to learn everything possible about the process directly from plumbing professionals. That experience led us to invest in our own equipment and train our entire team to perform smoke tests independently.

We use a professional Fog Trace machine by Sewer Assassin, equipment specifically designed for residential and commercial smoke testing. Our technicians are trained to operate it correctly, interpret the findings from a pest control perspective and document everything in a clear report.

If the smoke test identifies a breach that requires plumbing repair work we bring in a qualified plumbing company to address it. We share our findings and report with the plumbing team so they have a complete picture of what was found and where. Our role is to identify the pest entry source. Their role is to correct the plumbing. Together we close the loop on a problem that neither discipline could fully solve alone.

This means you don’t need to coordinate two separate companies from scratch. We manage the smoke test process, identify the findings and connect you with the right plumbing partner to get the repair work done.

When Should a Smoke Test Be Considered?

A smoke test is not the first step in every rodent situation and we want to be clear about that. The vast majority of rodent problems in South Bay homes are resolved through inspection, trapping and exclusion work. A smoke test becomes worth considering when a more conventional approach has been thorough and complete and activity is still persisting in a way that doesn’t make sense given what’s been done.

Specific situations where a smoke test may be worth exploring include homes with older plumbing systems that may have deteriorated connections or joints, homes that have had renovations or remodels where plumbing work was involved, properties with persistent rodent activity concentrated near bathrooms, kitchens or utility areas and cases where game camera or trap activity consistently points to a pattern of entry that can’t be explained by any identified exterior opening.

If you’ve been dealing with a rodent problem that keeps coming back despite thorough professional treatment, a plumbing breach may be worth investigating. Our team can assess whether a smoke test makes sense for your specific situation and take it from there.

Frequently Asked Questions

Is the smoke used in a smoke test safe?

Yes. The smoke is non-toxic artificial smoke that dissipates quickly and leaves no residue. It poses no risk to people, pets or the structure and is specifically designed for diagnostic use in occupied residential and commercial buildings.

Can rats really travel through plumbing to get into a home?

Yes and the biology makes it very possible. Rats can hold their breath for up to three minutes and tread water for up to 72 hours. That breath-hold capacity is more than enough to navigate a toilet U-bend or a flooded pipe section. Combined with their collapsible rib cages that allow them to squeeze through very tight passages, a rat that finds an opening connected to your sewer line has the physical tools to follow it into your home.

Do I need to hire a plumber separately to get a smoke test done?

No. Our team at ASPCW is trained and equipped to perform smoke tests independently using our own professional trace machine. We handle the entire smoke test process, document our findings and share a full report. If the test identifies plumbing breaches that require repair work we coordinate with a qualified plumbing company on your behalf. You don’t need to manage two separate companies from scratch.

How do I know if a plumbing breach might be causing my rodent problem?

The clearest signal is persistent rodent activity in a home where thorough exclusion work has been completed with no identifiable exterior entry points remaining. If activity is consistently concentrated near plumbing areas, if you have older plumbing that has never been inspected or if you’ve had any renovations that involved plumbing work, those are all factors worth discussing with us. Our team can assess your specific situation and advise whether a smoke test is the right next step.

Will a smoke test always find the source of a rodent problem?

A smoke test is specifically designed to identify breaches in the plumbing system and it’s highly effective at that. If rodent entry is through a plumbing breach a smoke test will very likely find it. If entry is through a structural gap, roofline vulnerability or other non-plumbing source a smoke test won’t identify that. It’s a tool we reach for when conventional inspection methods have been exhausted and the evidence points toward a plumbing source. We’ll always be honest with you about whether it’s the right next step for your situation.

Still Dealing With Rodents After Everything You’ve Tried?

If you’ve had professional treatment, exclusion work has been completed and you’re still seeing activity, a plumbing breach may be the piece of the puzzle that hasn’t been looked at yet. Give us a call and let’s talk through your situation. We’ll give you an honest assessment of whether a smoke test makes sense and what the right next steps look like.

American Structural Pest Control West

Phone: (310) 699-3110

Email: office@aspcwinc.com

Website: aspcw.com

Serving Torrance, Redondo Beach, Hermosa Beach, Manhattan Beach, El Segundo and throughout the South Bay.