How Do Plumbers Find Sewer Gas Leaks?
Plumbers find sewer gas leaks by inspecting P-traps, toilet seals, drains, cleanouts, drain connections, and plumbing vent systems for problems that could allow sewer gas to escape. When the source can’t be found visually, a plumber may perform a plumbing smoke test. This introduces visible smoke or fog into the drain, waste, and vent (DWV) system so hidden leaks and openings can be easier to locate.
Sewer gas leak detection can be challenging because the location where a customer smells the odor isn’t always where the plumbing problem is located. Sewer odors can travel through wall cavities, ceilings, utility spaces, and other areas of a building.
Here are some of the methods professional plumbers can use to find the source.
1. Inspect Common Sources of Sewer Gas
A plumber will typically begin with a visual inspection of the plumbing system and fixtures.
Common areas to inspect include:
- Toilets and toilet seals
- Sinks and drains
- P-traps
- Floor drains
- Cleanouts
- Drain connections
- Exposed DWV piping
- Plumbing vents
- Pipe fittings and joints
Signs of damage, loose connections, missing components, or improper installation can help narrow down the source of a sewer gas smell.
If nothing obvious is found, additional testing may be needed.
2. Check P-Traps and Floor Drains
A dry P-trap can be a potential source of sewer odors.
P-traps are designed to hold water, creating a barrier between the building and gases inside the drainage system. When a sink, shower, floor drain, or other fixture isn’t used for an extended period, the water inside the trap can evaporate.
Plumbers may check trapped fixtures to determine whether the water seal is present and functioning correctly.
If restoring the water seal eliminates the odor, a dry trap may have been contributing to the problem. If the sewer smell continues, further investigation may be necessary.
3. Inspect Toilets and Plumbing Seals
Toilets are another common area plumbers may investigate when trying to find a sewer gas leak.
A damaged or improperly sealed toilet connection may allow sewer gas to enter the building even when there isn’t an obvious water leak.
A plumber may inspect the toilet for movement, damaged seals, installation problems, or other signs that the connection to the drainage system needs attention.
4. Check the Plumbing Vent System
The plumbing vent system helps regulate pressure within the drainage system and provides a route for sewer gases to exit the building.
Problems with the vent system can contribute to sewer odor complaints.
A plumber may inspect for:
- Damaged vent piping
- Loose connections
- Improperly installed vents
- Open or disconnected pipes
- Other defects in the vent system
Finding a plumbing vent leak can be more difficult when the piping is concealed behind walls or above ceilings. When visual inspection isn’t enough, additional diagnostic testing may be useful.
5. Perform a Plumbing Smoke Test
When the source of a sewer gas smell isn’t visible, plumbing smoke testing can help locate hidden leaks and openings in a DWV system.
During a plumbing smoke test, visible smoke or fog is introduced into the drain, waste, and vent system through an appropriate access point. The plumber then inspects the property for smoke escaping from areas where it shouldn’t.
Escaping smoke can help identify potential problems such as:
- Cracked or damaged DWV piping
- Loose plumbing connections
- Failed seals
- Toilet connection problems
- Plumbing vent defects
- Open or damaged cleanouts
- Improper plumbing connections
- Hidden openings that may allow sewer gas to escape
This makes a plumbing smoke test particularly useful when a customer reports a persistent sewer odor but a standard inspection doesn’t reveal the source.
How Does a Plumbing Smoke Test Help Find Sewer Gas Leaks?
A plumbing smoke test helps plumbers locate potential sewer gas leaks by making otherwise invisible openings easier to identify.
When fog is introduced into a properly prepared plumbing system, it travels through the DWV system. If there is an opening or defect, visible fog may escape from that location.
Instead of relying solely on where someone smells sewer gas, the plumber has a visual indication of an area that may require further investigation.
This can be particularly useful for problems located behind walls, above ceilings, around plumbing fixtures, or in other difficult-to-inspect locations.
Using the FogTrace™ Plumbing Smoke Testing Machine
For plumbers who regularly troubleshoot difficult sewer odor problems, the FogTrace™ Plumbing Smoke Testing Machine provides a reusable method for performing professional plumbing smoke tests.
FogTrace™ generates high-volume visible fog that can be introduced into the plumbing system to help technicians identify areas where fog is escaping.
Features include:
- Push-button operation
- High-volume fog output
- Wireless remote operation
- No open flame
- Reusable for repeated testing
- Designed for professional plumbing diagnostics
Unlike traditional single-use smoke bombs, the FogTrace™ system uses High density fog fluid. It’s incredibly easy to source and inexpensive.
For plumbing contractors who regularly receive calls involving unexplained sewer odors, an easy to use economical plumbing smoke test machine can provide a better diagnostic tool for identifying difficult-to-find problems.
Why Are Sewer Gas Leaks Difficult to Find?
Sewer gas leaks can be difficult to locate because where the odor is noticed may not be where the plumbing defect is located.
Air movement can carry odors through:
- Wall cavities
- Ceilings
- Utility chases
- Mechanical spaces
- Openings around pipes
- Other areas of a structure
For example, a customer might notice a sewer smell in a bathroom even though the actual opening is somewhere else in the DWV or plumbing vent system.
This is one reason smoke testing for sewer gas leaks can be valuable. Instead of trying to locate a problem based solely on odor, the plumber can look for visible fog escaping from the system.
Can a Plumbing Smoke Test Find a Leak Behind a Wall?
A plumbing smoke test can help plumbers narrow down the location of a potential hidden leak or opening behind a wall, ceiling, or other concealed area.
If smoke introduced into the DWV system becomes visible around a wall, ceiling, plumbing penetration, fixture, or another unexpected location, the plumber has an area to investigate further.
Smoke testing doesn’t necessarily determine the exact type of plumbing defect. Instead, it can help identify where further inspection may be necessary, potentially reducing unnecessary exploratory work.
When Should a Plumber Consider Smoke Testing?
A plumber may consider a sewer smoke test when:
- A customer repeatedly reports sewer odors
- The source of the sewer smell isn’t visible
- P-traps and fixtures appear to be functioning correctly
- A hidden DWV leak is suspected
- A plumbing vent problem is suspected
- Previous repairs haven’t eliminated the odor
- The suspected problem is behind a wall, ceiling, or floor
- A commercial property has an unexplained sewer odor
The appropriate diagnostic method will depend on the property, plumbing system, and suspected problem.
Find Sewer Gas Leaks With Less Guesswork
Finding a sewer gas leak isn’t always as simple as following the smell. Plumbers may need to inspect P-traps, toilet seals, drains, cleanouts, DWV piping, and plumbing vents before determining where the problem originates.
When a visual inspection doesn’t reveal the source, plumbing smoke testing can provide another way to investigate hidden openings and defects.
The FogTrace™ Plumbing Smoke Testing Machine gives professional plumbers a better smoke-testing solution for diagnosing difficult sewer odor problems and incorporating smoke testing into their plumbing services.
Find the source. Reduce the guesswork. Diagnose difficult sewer odor problems with FogTrace™.
Frequently Asked Questions About Sewer Gas Leak Detection
How do plumbers find sewer gas leaks?
Plumbers typically begin by checking P-traps, toilets, drains, seals, cleanouts, DWV piping, and plumbing vents. If the source isn’t visible, a plumber may perform a smoke test to help locate hidden openings by introducing visible smoke or fog into the plumbing system and observing where it escapes.
What is a plumbing smoke test?
A plumbing smoke test is a diagnostic procedure that introduces visible smoke or fog into a building’s drain, waste, and vent system. Smoke escaping from an unexpected location can help a plumber identify an area that may contain a leak, failed connection, damaged seal, or other plumbing defect.
Can a smoke test detect a sewer gas leak?
A smoke test can help identify openings in the DWV system that may allow sewer gas to enter a building. Escaping smoke provides a visible indication of where a plumber should investigate further.
Can a bad toilet seal cause a sewer smell?
A damaged or improperly installed toilet seal or connection can potentially allow sewer gas to enter a building. This is one of the areas plumbers may inspect when diagnosing an unexplained sewer odor.
Can sewer gas come from a plumbing vent?
Problems involving plumbing vents can contribute to sewer gas odors. Damaged, disconnected, or improperly installed vent piping may create an opening that requires further investigation.
Can a plumbing smoke test find leaks behind walls?
A smoke test can help indicate that an opening exists in a concealed area. If fog becomes visible around a wall, ceiling, fixture, or plumbing penetration, it can help the plumber narrow down where additional investigation may be needed.
What equipment do plumbers use for smoke testing?
Professional plumbing smoke testing typically requires a method of generating visible smoke or fog and introducing it into the DWV system. The FogTrace™ Plumbing Smoke Testing Machine is designed to generate high-volume fog for professional plumbing diagnostic applications.
