Why Does Your Drain Smell and What Can You Do About It?

Why Does Your Drain Smell and What Can You Do About It?

Customer with bad smell from plumbing drain
Customer with bad smell from plumbing drain

Recent surveys reveal that the way your home smells leaves a long-lasting impression on guests. Good or bad, you need to deal with the smells that leave an indelible stamp on your reputation.

So when a raunchy drain smell begins to seep through your plumbing drain, you have a couple of problems. One, people are going to think that you stink. Two, you may have a serious issue with your plumbing.

As you’re pondering the question, “Why does my drain smell?” you find some peace knowing that a bad drain smell doesn’t always mean an upcoming plumbing disaster. You may just need a drain cleaning service to clean out a pipe or two.

By the time you’ve finished reading this article, you will understand several things that could be causing your drain smell.

Problems With Your Trap

Plumber working on a kitchen sink drain
Plumber working on a kitchen sink drain

Beneath your drain, you should have a bend in the pipe. When you run water, the water will collect in the bend. This water then naturally blocks sewer gases from coming through the drain.

Gravity keeps the water in the pipe. Every time you run water, the water in the bend refreshes. The pipe typically makes a “p” shape, and thus plumbers refer to this bend as the P-trap.

If you have a bad smell coming from your drain, you could have problems with the trap. For example, you may have a leak in the trap which causes water to escape. With no water in the trap, there’s nothing to block the sewer gas. You will know there’s a leak if you either see water under the sink or if the water ceiling and walls beneath the sink are discolored.

If you don’t run water through that particular faucet much, the water in the trap will evaporate. This is why your drain may smell after you return home from a two-week vacation. You simply need to run water in the drain for a few seconds to fill the trap.


Check to make sure you actually have a trap. Very old homes will not have a trap, and thus there’s nothing to block the sewer gas smell. A plumber can install the trap in homes that do not have one.

Mold and Mildew

When you have a leaky pipe and don’t care for it, the sink will start to smell bad. Water will soak into the materials around the sink. A moist, warm environment is the ideal growing place for mold.

Unattended, the mold will not just cause a bad smell. Your home’s occupants can develop allergies and life-altering illnesses when exposed to mold over a long period of time.

If you have mold and mildew, call in a professional mold mitigation service to care for the issue. Do not attempt to clean the mold on your own. This will ensure the overall health and safety of your home’s occupants.

Bacteria Growth in Your Plumbing Drain

Dirty and Smelly P-Trap
Dirty and Smelly P-Trap

Bacteria is a natural part of the plumbing system. If you have too much bacteria or the wrong type of bacteria, though, it can cause an odor.

If you’re sure there’s no leak causing the smell, the most likely culprit is bacteria. Bacteria are a natural part of your plumbing system, but when too many, or the wrong kind accumulate, they can cause terrible odors.

Over time, organic matter will accumulate in your sink as well. In a kitchen sink, grease and food scraps begin to stick to the sides of the pipe. In a bathroom sink, soap, grease, and hair will accumulate.

Bacteria will grow in this matter, and it will smell pretty awful. To clean the pipes and get rid of the smell, you will need a professional drain cleaning service to first detect and ultimately for your problem.


Before the drain cleaning service arrives, you can try a few other home fixes such as pouring a kettle of hot water down the drain or sprinkling baking soda on the drain and then following it with a cup of white vinegar after a few minutes.

These organic fixes will help for a short amount of time, but a professional drain cleaning service will help the smell stay at bay for much longer.

It’s also worth noting that a well-intentioned home solution can actually cause more problems. Many pipes and plumbing systems aren’t designed for extremely high temperatures assaulting them all of sudden. Some modern plastic may deform, weaken, or even break.

Your local hardware store will have an aisle full of harsh chemicals as well that promise to break up grease and open up a drain. Many plumbers discourage homeowners from using such chemicals. They also can weaken pipes which will lead to leaks in time.

Clogged Sewer Vent

Every home has a sewer vent on its roof. It looks like a small pipe protruding from your roof. Sometimes the sewer vent will be clogged, and this can cause a bad smell in your drains.

The clog could come from an animal getting into the vent pipe and dying. It could also happen in extremely cold weather when the vent ices over.

A qualified plumber will be able to diagnose and then fix this problem.

Dirty Disposal

Plumber working on a kitchen sink drain
Plumber working on a kitchen sink drain

If your kitchen train smells, you may just need to clean your garbage disposal. Whenever you run your disposal, make sure you’re running hot water in the drain as you flip the switch for the disposal. If water does not adequately rinse food from the disposal blades, it will begin to rot and make your drain stink.

You also can have smelly disposal when you overload it. If you’re packing organic matter into the disposal, it may not have the power to properly grind it and rinse it down the drain.

You can clean the disposal naturally by running ice cubes, coarse salt, lemon peels, and cold water down it. If you can’t get rid of the smell, you need to replace the disposal.

Deal With the Drain Smell

Whatever may be causing your plumbing drain smell, deal with it. You have several things to look for now, so begin by testing your P-trap, and then move into calling a drain cleaning service.

Do you have a smelly drain? If so, contact us. Our plumbing experts are ready to help you fix the problem and have your home smelling sweet once again.

More Helpful Resources:

Plumber unclogging a shower drain
how to unclog any drain

Dirt pipe before and after comparison
Dirty drain pipe before and after cleaning

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