Why Does My Shower Drain Smell? How to Get Rid of the Odor

There’s nothing worse than getting ready for a nice, refreshing shower only to find that the drain smells bad. There are a number of reasons a shower drain may have a foul smell, including clogged or leaking pipes, a dry or dirty P-trap, and a build-up of biofilm. In this article, we’ll teach you how to identify why your shower drain smells, as well as how to fix common problems.

Causes of Smelly Shower Drains

If your drain smells and doesn’t drain properly, it’s probably clogged.
If it smells like sewage or rotten eggs, you may have a dry or dirty P-trap or a pipe leak.
If it smells like mildew, there’s probably biofilm build-up.

Section 1 of 5:

Identifying the Source of the Smell

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If your shower also isn’t draining properly, it’s likely clogged. If you notice your shower takes a long time to drain, or isn’t draining at all, in addition to the odor, it’s probably time to unclog it. Over time, things like dirt, grime, hair, and other debris build up and get trapped in the drain line. Within a few days or a few weeks, this build-up will likely start to smell.^{[1]
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- It’s also possible that there are air bubbles trapped in the plumbing lines, which can cause water to drain more slowly and trap bad-smelling gases.
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If it smells like sewage, you likely have a dry or dirty P-trap. The P-trap is the U-shaped section of the pipe that dips below the rest of your shower drain line before connecting to your main stack. It’s designed to hold enough water at all times to prevent gases from your sewer line from escaping through your drains. If you smell sewage, it likely means your P-trap isn’t holding water as it should.^{[2]
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- If the odor doesn’t smell like sewage and is instead more musty, the P-trap could be dirty. Cleaning it could solve the problem.
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If the drain smells like mildew, it may have biofilm build-up. Biofilm is a mucky, slimy substance formed from bacteria and bacterial waste that often gets mistaken for mold. In addition to a mildewy smell, you may notice a pink or orange growth in or around the drain.^{[3]
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- It’s important to remove biofilm as soon as possible, as certain types can spread Salmonella and E. coli, as well as infect open wounds and cause urinary tract and respiratory problems in those with compromised immune systems.
- Biofilm may also contain a build-up of body oil, hair, and/or soap scum. These all produce a similar odor.
- It’s possible your drain could have actual mold, as well. The smells are similar, but true mold won’t have the pinkish color that biofilm does.
When a pipe leaks, it can let sewer gases into your bathroom, which often smell like rotten eggs or sulfur. The smell is similar to having a dry P-trap, so try addressing that issue first. If the smell doesn’t go away, it may be time to hire a professional to see if you have a leak.^{[4]
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Section 2 of 5:

Unclogging a Shower Drain

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Feed a drain snake down the drain to unclog it. While there are several ways to unclog a shower drain, using a drain snake is one of the most popular. Choose a snake with a 1/4 or 5/16-inch (0.6 or 0.8 cm) cable so it’s flexible enough to curve through your pipes. Then, simply guide the snake down the drain until you feel it hook on the clog, then pull it back up. Or, try an alternative unclogging method below:^{[5]
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- Pull the clog out by hand if you can reach it.
- Pour boiling water down the drain to dislodge the obstruction.
- Use a plunger to draw the clog to the surface. This is also the best way to remove trapped air bubbles that may be causing the odor.
- Pour a chemical cleaner down the drain to dissolve the clog.
- If none of these methods work, it may be time to call a professional.
EXPERT TIP

Chris Willatt
House Cleaning Professional
Chris Willatt is a House Cleaning Professional based in Denver, Colorado. Chris is the owner of Alpine Maids, a cleaning agency that he founded in 2015. Chris is on a mission to elevate what it means to be a cleaning professional and has built up Alpine Maids with that goal in mind. Chris has been featured in USA Today, Forbes, and Readers Digest. Alpine Maids received Angie's List Super Service Award for three years in a row from 2016-2018. They were also awarded Colorado's "Top Rated Local House Cleaning" Award in 2018 and were featured on the Inc. 5000 Company List.

Chris Willatt
House Cleaning Professional

Clean your shower drain once a week. Make sure you're getting all the hair out, and remove anything that's stuck in the drain. If the drain is already clogged, your best bet is either a coat hanger or a drain snake.

Section 3 of 5:

Cleaning a Shower P-Trap

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Clean your P-trap with baking soda and vinegar. Pour 1/2 cup (125 g) of baking soda, then 1/2 cup (118 ml) of distilled white vinegar down the drain. Cover the drain with a stopper or plate and allow the baking soda and vinegar solution to froth up and clean the inside of the drain and P-trap. This should clear out any grime or debris causing the odor.^{[6]
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- It’s possible to use bleach or other cleaners to clean your P-trap, but harsh chemicals can damage your pipes if used too frequently. Try home remedies first before resorting to harsher solutions.
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Run your water to fix a dry P-trap. If you rarely use the shower you notice the smell coming from, the water may have simply evaporated from the P-trap. Try running your water for a few minutes or pouring 1 or 2 cups (236-473 ml) down the drain.^{[7]
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Research source} Come back in an hour and look down the drain to make sure you can see the water. If you rarely use the shower, pour 4 oz (118 ml) of mineral or cooking oil down the drain to slow evaporation.
- If you use the shower frequently and it smells, there may be another problem with your P-trap, and your best bet is to call a professional plumber.

Section 4 of 5:

Cleaning Biofilm Build-Up

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Scrub biofilm stains around your drain and on your tiles. If you notice biofilm around your shower drain, break down the layers of grime by scrubbing it with a cleaning brush. Then, spray the affected surface with an antimicrobial disinfectant. Repeat this process weekly to prevent the biofilm from coming back.^{[8]
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- In the case that the biofilm isn’t actually in your drain, this should be all you have to do.
- Another option is to scrub around the drain with a paste made from baking soda and water. This will also help remove mold.
- A great way to prevent biofilm build-up is to clean your shower drain regularly. House cleaning professional Chris Willatt says to “just pick the hair out as best you can and then hit it with a scrub brush.”^{[9]
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Clean the inside of the drain with a paint roller cover. Remove your drain cover and clean it with a disinfectant or other antibacterial cleaning product. Then, dip a fuzzy paint roller cover (or a cleaning brush with a long shaft) in a cleaning solution of your choice and push it vertically down the drain. Turn the cover to break up the biofilm, then pull it out. Rinse it in hot, soapy water, then repeat the process until it comes out clean and you no longer see any biofilm.^{[10]
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- If you suspect there’s mold as well, boil 10 qts (9 L) of water, let it cool, then slowly pour it down the drain. Follow up with a cup (236 ml) of vinegar, then 1/2 cup (125 g) of baking soda.

Section 5 of 5:

When to Call a Professional

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Call a plumber if you can’t fix the problem yourself. If you’ve tried the above DIY methods and they didn’t work or you suspect your pipes are leaking, it’s time to hire a professional. A professional plumber can fix the leak and address any additional damage, like rot or mold, in the surrounding infrastructure. Pros can also fix clogged vent lines that sometimes cause dry or dirty P-traps.^{[11]
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- Finding leaks can be very difficult to do on your own, as your drain lines are typically located deep within your walls and floor, so don't try to tackle this issue yourself.
- If you suspect you have a leak, call a pro as soon as possible. A plumber can locate the leak, fix the plumbing line, and suggest the next course of action. The longer the leak remains, the more water damage it will cause.

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To help prevent clogs, consider using a shower drain hair catcher to prevent hair and other large debris from going down the drain.

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Warnings

If you choose to use bleach, do not mix it with any other chemicals unless you’re certain it’s safe to do so. Mixing it with the wrong chemicals can create toxic fumes.^{[12]
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