Smelly Shower Drain? Here's What Might Be Happening

Why does my shower drain smell bad?

Do you feel like you can’t enjoy long hot showers because of dreaded shower odors? A smelly shower drain can ruin a relaxing experience for you and the people you live with.

Several things can cause shower drain smells. Figuring out what these could be is the first step you can take to fix the issue.

If your shower drain smells, there are often three common culprits:

  • Mold growth in your shower drain cover
  • Biofilm buildup in your shower drain
  • Foul-smelling sewer gases flowing back from clogged pipes

This article will help you determine what’s causing that annoying shower drain smell. You can also find helpful tips and methods to resolve shower drain odors.

What Causes a Smelly Shower Drain?

Shower drain smells can develop from various situations. Generally, you may identify the cause simply from the scent you smell while in the bathroom. If you’re unsure of the smell, getting help from a professional is ideal.

Musty Bad Smell from Shower Drain

A musty smell normally indicates mold growth in your shower drain or drain cover. Mold spores release an odorous gas as part of their metabolic process.

If inhaled, this must-scented gas can cause headaches, dizziness, nausea, and fatigue. It may also cause more severe illnesses such as cancer and other respiratory conditions.


When heat and moisture are present in your bathroom, it creates the perfect environment for mold to grow. Mold thrives in moist, warm, and dark spaces, making your shower drain an ideal home.

If you suspect your shower drain has a mold infestation, it must be addressed immediately to avoid endangering yourself and your loved ones.

How to remove mold from shower drain and drain cover?

There are easy ways you can get rid of mold from your shower drain. If you’re not confident about your DIY home improvement skills, calling a professional plumber to do maintenance and repairs for you would be more effective.

Gather the following:
  • Boiling water
  • An old toothbrush
  • Baking soda
  • White distilled vinegar
  • A small basin
Follow these steps to effectively kill mold in your shower drain:
  • Combine one equal parts of water and baking soda in a container
  • Mix with a spatula or wooden stirrer until it forms glue like substance
  • Take your old toothbrush and use it to apply the paste to the shower drain
  • Leave the mixture on the drain for about 10 minutes
  • Scrub the drain and drain cover using the toothbrush; repeat this as many times as you need to loosen the mold growing in and around the shower drain.
  • Boil 11 liters of hot water in a pot
  • Slowly pour the water into the shower drain
  • Wait a few minutes then pour a cup of distilled vinegar after the water
  • Next, measure one cup of baking soda and pour it down the drain

This method should help remove the mildew smell from your bathroom drains. You can also use it to clean other drains in your home, including your kitchen sink and bathroom sink drain.

If the smell persists even after conducting this cleaning method, you might have a more severe infestation in your bathroom.

Mold problems of a bigger size require expert and professional cleaning. A plumbing professional will have the skills and tools to fix your shower drain issue.

IMPORTANT: Hot water can damage PVC piping and melt pipe connectors. Remember to let the water cool a bit before you pour it down the drain.

Shower Smells Like Rotten Eggs and Sewage

A rotten egg smell in your bathroom typically means there’s a clog in your shower drain caused by biofilm buildup. It could also mean that sewer gases are flowing back through your drain.

What Causes Biofilm Drain Clogs?

If you’ve ever wondered what that thin white layer of gunk on your shower drain is, here’s your answer: Biofilm.

Biofilm is a combination of your body oils, hair, shampoo, soap scum, mineral deposits, and dead skin that accumulate on your shower drain cover and pipes. It’s the perfect breeding ground for odor causing bacteria—it’s also what makes your bathroom smell like rotten eggs.

How to Remove Biofilm from the Shower Drain?

To remove this unpleasant smell, you need to eliminate the biofilm from your drain.

Gather the following:
  • Drain brush cleaner
  • Baking soda
  • Boiling water
  • White distilled vinegar
Perform the following steps to eliminate biofilm buildup in your pipes and drains:
  • Remove the drain cover
  • Boil 11 liters of water in a pot and slowly pour it down the drain
  • Next, measure one cup of distilled vinegar and pour it in after the water
  • Measure half a cup of baking soda and pour that in as well
  • Let this rest for 2 hours before pouring boiling water down the dirty drain for a second time
  • Using the drain brush, scrub in and around the drain to loosen and remove residue
  • Give it a final rinse with clean water

The unpleasant smell in your shower should go away right after. If the issue persists, it might be a great idea to get professional drain cleaning.

How to Prevent Biofilm from Reforming?

Picking up stray hair from your shower floor after you take a bath is a simple way you can prevent biofilm from reforming on your shower drain. Regularly cleaning your shower drain is also a great idea. You can use a drain snake to remove barriers in a clogged drain.

What Causes sewer Gas backup?

Another reason for that rotten egg smell in your shower is a blocked sewer line that’s causing sewer gases, also called hydrogen sulfide, to flow back into your home.

Although a sewer backup isn’t necessarily a health hazard, that sewage smell can still put everyone in your home in an uncomfortable position.

Sewer gas backups are often a result of blocked plumbing vents, a dry P-trap, or a sewer backup.

An experienced DIY-er might be able to address a dry P-trap independently. If you’re dealing with blocked plumbing vents or a sewer backup, licensed plumbers would be more effective at resolving the problem.

What is a P-trap?

The shower P-trap is a u-shaped pipe positioned below the shower drain. It needs to contain a small amount of water to continue functioning optimally.

The P-trap is responsible for catching dirt and debris in the drainage pipes, preventing them from traveling into your plumbing system. It also stops sewer gases with that horrible sewer smell from crawling back through your drain.

How to fix a dry P-trap?

To identify if the P-trap is indeed the problem, you first should check your drain for water in the pipe. If your pipes have water but the sewer smell still persists, talking to a plumbing professional would be more helpful. There could be something else that’s causing foul smells to emanate from your drain pipes.

On the other hand, if your P-trap is indeed dry, you can follow these steps to fix the problem:

  • Measure one to two cups of water and pour it down the drain
  • Leave it there for about an hour
  • Come back and peek into the drain to see if the water stayed in the P-trap

If the water is still there, it should solve the dry P-trap problem. However, if the water disappears from the P-trap after an hour, you may be dealing with leaky pipes and need the assistance of a licensed plumber to replace or repair them

Get Rid of Unpleasant Shower Drain Smells

Your plumbing system requires consistent professional maintenance to ensure everything is functional and clean. If you forego the regular and necessary repairs or maintenance tasks, shower odors, leaky pipes, and drain clogs are just some of the things that you can expect to happen.

Shower drain odors caused by leaky pipes and bacterial waste can ruin your overall experience of your bathroom. Soap scum, body oils, and dead skin can accumulate in your plumbing pipes, creating all sorts of problems for your plumbing system. Professional drain cleaning can keep your shower smelling fresh all year round—not to mention prevent more serious problems from developing in your sewer line.

Mac 5 Drain Cleaning Experts

Whether it’s an annoying shower drain smell, pink mold, or a leaking drain pipe, our expert service technicians are more than ready to offer you the right solution. We train all our employees in the latest techniques and methodologies, making sure they know how to handle sensitive equipment and avoid poor installation jobs.

All our tools are up to date to make sure we adhere to the current trends and standards of the industry. You can trust our teams to take care of everything from leak detection and hydro jetting to sewer line repair.

Get in touch with us today to learn more about our products and services.

Call 321-244-7500

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