Sewer Smells in the House: What Causes It and How to Fix It

Few things are more unpleasant than noticing a sewer smell inside your home. Whether it hits you in the bathroom, kitchen, basement, or laundry room, a strong odor often signals an underlying plumbing issue. The good news is that most causes of sewer smells in the house can be identified and repaired quickly—especially when addressed early.

A sewer odor is never something to ignore. In many cases, it points to a blocked drain, a dry trap, or a ventilation issue. In more serious situations, it could indicate a damaged sewer line or sewer gas leak. Understanding the most common causes can help homeowners know what to look for and when to call a professional plumber.

One of the most common reasons for sewer odors is a dry P-trap. P-traps are the curved sections of pipe under sinks, showers, and floor drains that hold a small amount of water. That water creates a barrier that prevents sewer gas from rising into the home. If a drain hasn’t been used in a while—such as a basement floor drain, guest bathroom sink, or laundry drain—the water can evaporate and allow sewer gas odor to enter the room. Running water for a few seconds often refills the trap and removes the smell.

Another frequent cause is a clogged drain or buildup inside the plumbing system. Grease, soap scum, hair, and debris can stick to the walls of pipes, collecting bacteria that creates foul odors. If the smell gets worse after using water or if drains are slow, it’s often a sign that professional drain cleaning services are needed. A thorough cleaning eliminates buildup at the source, not just the odor.

A more serious issue is a problem with the plumbing vent system. Plumbing vents release sewer gases safely through the roof and allow drains to flow properly. If a vent pipe is blocked by debris, leaves, snow, or animal nests, odors can back up into the home. Venting issues may also cause gurgling sounds, slow draining, or toilets that bubble when nearby sinks drain. In these cases, a professional plumber can inspect the venting system and restore proper airflow.

In some homes, sewer smells may be caused by a damaged wax ring under the toilet. This seal connects the toilet base to the drain pipe and prevents water and gas leaks. When the seal breaks down, sewer gases can escape around the toilet, often producing a strong odor that becomes noticeable after flushing. Replacing the wax ring is a common repair that can solve the issue quickly.

If the odor is persistent or widespread, the cause may be deeper in the system—such as a cracked drain pipe, damaged sewer line, or sewer line blockage. Sewer line problems may also come with additional warning signs like frequent backups, slow drains throughout the home, or soggy areas in the yard. In these cases, a sewer camera inspection is often the best solution to identify the source of the problem without guesswork.

At Woods Rooter, we help homeowners locate and eliminate sewer odors quickly and professionally. Whether you need drain cleaning, sewer line inspection, or repairs to eliminate sewer gas leaks, our team uses modern equipment to diagnose the issue and fix it the right way. If you’re noticing sewer smells in your home, getting it checked early can prevent costly damage and restore clean, safe indoor air.