Reasons Your Sink Drain May Smell

Homeowner cleaning a sink drain while calling a plumber - Mr. Plumber by Metzler & Hallam

Every now and again, homeowners have to deal with a foul sink drain smell. Not only are smells annoying to deal with, they cause discomfort for homeowners. In Indianapolis, Indiana, Mr. Plumber diagnoses these issues and provides helpful tips to get rid of the smell.

Whether you’re a new Indianapolis homeowner or a seasoned one, smelly drains are a nuisance. In this blog post, Mr. Plumber discusses why drains give off a foul odor. After learning the cause, removing the smell becomes easy. Let’s take a look at everything about drains!

Reasons For a Sink Drain Smell

The reasons for a sink drain smell range in severity. Some smells are attributed to something as simple as food, but others are more complex and require the help of a trained plumber. Before we get to that, the reasons for a sink drain smell need to be discussed. 

  • Dry p-trap. Not many homeowners know about the p-trap. The p-trap is installed under all the sinks in your home. It’s main purpose stems from trapping debris before it goes down the drain. This prevents clogs from forming deep within the plumbing system. It also stops sewer gas from entering the home. When the p-trap gets too dry, those trapped odors from debris are released. 
  • Sewer line. Alternatively, if the p-trap got too full it might not have properly prevented a clog from forming lower down in the plumbing. A blockage deep in the sewer lines causes a sink drain to smell, but surface-level fixes are rarely enough to clear the clog. Additionally, sewer gas rises up through drains with empty drain traps. Mostly, this occurs to infrequently used drains around the home.
  • Rotting food. Rotting food likely caused your sink drain smell. It’s possibly the most common cause for a smelly drain on this list. If you frequently put food down the drain, some of it may stick to the sides of the pipe or within the garbage disposal unit. Even if most of the food goes down without a problem, the tiniest amount of food in the drain rots and causes a foul odor.
  • Venting problems. Sewer gas also gets trapped by venting pipes. These pipes run sewer gases to the roof of your home. When they become clogged with outdoor debris—like snow, birds’ nests, or leaves—the sewer gas is forced back down and into your drains. Who would have thought your roof had something to do with your drains?
  • Clogs. Another common cause of sink drain smells are surface-level clogs. Hair, food, grease, soap, and other substances get stuck in your drains and cause clogs. Of course, over time these clogs begin to decay or collect other dirt and debris. Smells start to buildup until you are forced to take action. 
  • Mold or mildew. Because drains deal with water on a daily basis, mold and mildew have a good opportunity to grow. Mold and mildew thrive in dark, warm, and wet spaces. Though pipes aren’t always warm, they still house bacteria, which causes mold growth. 

Ways to Get Rid of the Sink Drain Smell

Now you know some of the most common causes of the dreaded sink drain smell, we move on to discuss ways to get rid of foul drain odors. For the most part, these methods are safe for homeowners to attempt. Odors caused by clogs, dryness, and similar issues are relatively easy to take care of for homeowners of all skill levels. For more major issues, it’s best to call in a professional plumber for help. 

  • Boiling water. If you suspect a clog, pour boiling water down the drain. Small clogs get dislodged easily with a quick flush with hot water. Larger blockages, at the very least, shrink in size. To combat the smell immediately with this method, add some essential oils or lemon juice to the water before you pour it in. 
  • Vinegar and baking soda. For tougher clogs, it’s time to break out the science fair kit. Boil some water, then gather your vinegar and baking soda. Make sure to cover the second drain in your sink if there is one. Pour some baking soda down the drain, then the vinegar. This causes a chemical reaction. The solution bubbles through the clog and disintegrates it. To finish it off, flush the solution down with the boiling water. No more clog means no more smell!
  • Plunger. Another way to combat smelly clogs from any drain deals with a plunger. Plungers work for clogs all over your home—not just the bathroom. Fill the sink with a little water, then plunge for about 20 seconds. Again, make sure the second drain is covered. When you lift the plunger, let water drain into pipe without any air pockets. The clog gets pushed down the pipe! 
  • Snake or auger. The last way to combat a sink drain smell caused by a clog requires a snake. Snakes, or augers, are long pieces of metal or plastic that hook onto clogs for easy removal. When the snake connects with the clog, give it a little twist, then pull out the clog and dispose of it in the garbage. 
  • Citrus rinds. For sinks with garbage disposals, try tossing some citrus rinds into the drain. Turn on the garbage disposal and let the rinds get chewed up. Not only does this combat the odor, it also cleans the garbage disposal. Lemons are the most common choice for this task. Use either the rinds or the fruity part of the lemon to help with the smell.
  • Water through the pipes. Dry p-traps from unused drains have an easy fix for a foul sink drain smell. Simply run water down the drain from time to time to ensure the p-trap stays moist. It’s best to run water through unused drain at least once a week.
  • Clear the venting pipes. Take a look at the amount of debris on your roof. Is there a lot? If so, there may be blockages to your venting pipes. Though homeowners attempt debris removal on their own, it is usually best to call for assistance with roof clearing. Professionals know exactly where to look for venting pipe blockages.
  • Call a professional. Issues concerning mold and mildew usually require the help of a professional. Besides the musky odor, the mold and mildew may have contaminated further down the plumbing system than you originally thought. In that case, it’s best to have a professional around to make sure the plumbing stays safe to use.

What Not to Do

Along with all of the great methods to get rid of a sink drain smell listed above, there is one course of action homeowners need to stay away from. Unfortunately, many homeowners use this method when they’re in a pinch. However, it ends up causing more harm than good.


  • Chemical cleaners. Advertised as the end-all-be-all of clog removal, chemical cleaners use harsh chemicals to cut through grease and other stubborn clogs. They do a good job of clearing clogs, but they also ruin your pipes. The chemicals eat away at the clog and at your pipes. This leads to irreversible corrosion which causes leaks at best, and burst pipes at worst. 


Make sure to attempt all of the other methods on this list and avoid chemical cleaners. If the methods stated above are unable to remove a clog, call in a professional plumber to clear it for you.

How to Prevent the Sink Drain Smell

There are a few different ways for homeowners to prevent a sink drain smell. They’re all easy and take very little time to complete. 


  • Keep the drain clean. Frequent cleaning sessions for your drain ensures foul odors stay away. To do this, either flush the drain with a boiling water and lemon mixture once a week, or grind lemon rinds in the garbage disposal. Both of these things combat smells as they accumulate over time.
  • Avoid food waste. Additionally, avoid putting food down the drain. You never know which food dump causes your drain to clog, so avoid the situation altogether by throwing away food in the trash.
  • Continuous use. The p-trap needs to always have water around to keep it from smelling. To avoid any smells caused by p-trap dryness, make sure to use all of the sinks in your home at least once a week. This ensures no p-trap goes without the water it needs to trap the smell.
  • Preventative maintenance. Preventative maintenance by trained plumbers ensures your pipes, drains, and other plumbing equipment runs like it’s brand new. Preventative maintenance checks are annual occurrences and don’t take up much of your time. 


Make the Right Decision

Now you know what causes sink drain smell, properly take care of the foul odor in the drain. Homeowners across Indianapolis, Indiana deal with this issue, but there are ways to handle this common issue. Use these tips from Mr. Plumber to get rid of sink drain smell.

For more information on Mr. Plumber’s services, visit our website. To schedule a maintenance check, give us a call today! We offer free estimates on our service right there on the phone.

Subscribe for Savings and Tips in Your Email!