For drain technicians encountering foul odors is an inevitable part of the job.

Sewer odor service calls can be challenging, requiring a deep understanding of sources, detection methods, causes and solutions.

Sources

Understanding the multiple sources of sewer odors is crucial for effective troubleshooting.

Dry traps: Dry traps occur when plumbing fixtures or drains do not receive regular use, causing the water in the trap to evaporate. This evaporation allows sewer gases, including hydrogen sulfide and methane, to escape into the surrounding area. To prevent dry traps, it is important to educate customers on the importance of regular water flow, especially in drains or fixtures that are not frequently used, such as guest bathrooms or basement drains.

Damaged or faulty pipe seals: Faulty seals, such as damaged wax rings in toilets or cracked vent pipes, provide an avenue for sewer odors to seep out. Over time, seals may become worn or damaged due to age, heavy use or improper installation. When inspecting a plumbing system, technicians should pay special attention to wax rings, flange connections and vent pipe seals, looking for signs of deterioration or cracks.

Blockages: Clogged or obstructed pipes disrupt the smooth flow of wastewater, leading to backups and odors. Hair, grease, solid waste and other debris can accumulate in pipes, creating an environment conducive to bacterial growth. Bacteria produce hydrogen sulfide, which gives off a characteristic rotten egg smell. Clearing blockages and implementing preventive maintenance measures are essential to combat this source of odors.

Detection

Accurate detection is critical for technicians to address sewer odor issues effectively.

Visual inspection: Conducting a thorough visual inspection of the entire plumbing system is essential in identifying potential sources of sewer odors. Technicians should examine vents, joints and pipes for any visible signs of damage or leaks. Look for cracks, corrosion, loose connections or missing seals. Additionally, inspect fixtures, traps, and drains for signs of dried-out traps or debris buildup.

Smoke testing: Smoke testing involves introducing artificially-produced smoke into the plumbing system to detect any leaks or cracks where odors may be escaping. The smoke, typically created with a non-toxic fog machine or smoke sticks, reveals air leaks or improper connections. Technicians should carefully block all outlets and openings in the system, excluding the access points being tested, to ensure accurate detection. Safety precautions and proper ventilation must be followed during this procedure.

Common Causes

Understanding the underlying causes of sewer odors allows technicians to address the root issues effectively.

Inadequate ventilation: Improper ventilation leads to the buildup of sewer gases within a plumbing system, resulting in unpleasant odors. Ventilation systems, including vent pipes and stacks, release sewer gases to the outside atmosphere. If vents are undersized or improperly installed, the system may not adequately disperse these gases. Technicians should assess ventilation systems, ensuring that the size, layout and location of vents comply with building codes and allow for proper airflow.

Debris and buildup: The accumulation of organic matter, grease and debris within the pipes fosters the growth of odor-causing bacteria. Over time, this buildup can compromise the integrity of the plumbing system, leading to the release of foul sewer odors. To effectively combat this cause, technicians should focus on thorough cleaning and regular maintenance.

Regular cleaning involves flushing drains and fixtures with hot water and suitable cleaning solutions to eliminate debris and bacterial growth. Jetting can be used to remove stubborn blockages and buildup from the interior of pipes. Additionally, auger cleaning  is useful for removing clogs caused by solid objects or tangled debris.

The use of drain strainers or filters can also help capture hair, food particles and other solid waste before it enters the plumbing system.

Aging infrastructure: Over time, pipes, seals and fixtures wear down, leading to cracks, leaks and damaged seals that allow sewer odors to escape. Aging infrastructure is a common cause of persistent sewer odors, especially in older buildings. Technicians should prioritize inspecting and repairing aging components, replacing them when necessary, to prevent future sewer odor issues.

Regular inspections should include checking for signs of corrosion, rust or weakened materials. If any components show signs of degradation, they should be promptly replaced to maintain airtight and odor-free connections.

About the Author

Anthony Pacilla is a registered master plumber for McVehil Plumbing in Washington, Pennsylvania. He has over two decades of experience in the plumbing and HVAC trades, and has a bachelor’s in business and economics from Thiel College.