How to Clean a Smelly Shower Drain: Causes & Fixes

A smelly shower drain is an indication of a problem in your plumbing system. You may have a sewer smell, musty smell, or even the smell of rotten eggs (sulfur smell) coming from the shower drain. These are caused by leaking pipes, a clogged drain, a dry P-trap, mold, biofilm, and others. 

I have found ways of fixing this using both DIY and commercial methods. If you can’t clean a smelly shower drain yourself, always consult a certified plumber before trying out something that might damage your drain. Luckily, there are a lot of DIY solutions I’ve tried out which work very well.

To clean a smelly shower drain, run hot water through the shower drain then pour in it a cup of baking soda. Add 2 cups of hot white vinegar. After 15 minutes, flush the drain with hot water. Repeat this procedure weekly to prevent shower drain smells. 

A clean shower drain has many benefits including limiting bad odors, reducing cleaning expenses, preventing of blockages, and reducing the health risks associated with dirty drains.

How to Clean a Smelly Shower Drain

Why does my shower drain smell?

There are various reasons behind the bad smell from the shower drain including the following:

Cause of a smelly shower drainSolutions/Fixes
A dry P-trapFill the P-trap with water or oil
Buildup of biofilmRemove biofilm from the shower drain
Clog in the shower drainUnclog the shower drain
Leaking pipesFix the leaks
Causes and fixes for a smelly shower drain

A dry P-trap

The P-trap of your shower drain works similarly to the P-trap of your toilet and other fixtures. It holds water in the bent neck to prevent sewer gases from flowing back into your home. As such, if there’s a sewage smell from the shower drain, it’s a dry P-trap that allows the gases from the sewer into the bathroom. 

A dry P-trap occurs due to the disuse of the toilet such that the water in the trap evaporates, or there’s a leak in the trap. In both cases, the P-trap doesn’t provide an airtight seal to keep the sewer gases away from the home. 

In some cases, the shower drain may stink because it has no P-trap installed hence there will be nothing keeping the sewer gases from entering the bathroom. 

Buildup of biofilm

Biofilm is the slimy layer of dirt and bacteria that grow on moist surfaces such as the inside of shower drains. It’s caused by the dirt that goes into the shower drain such as soap scum, shampoos, body oils, and many others. Biofilm has different colors although it’s commonly orange or pink in color that’s why it’s easily confused for pink mold. 

The presence of biofilm in the shower drain also encourages the growth of mold and mildew in it. As such, if the bathroom smells musty after a shower, it’s likely a mix of biofilm and mold spores. If the shower drain stinks without a musty smell, it’s only biofilm. 

Besides the stinky shower smell, biofilm is a health hazard since it can spread diseases and infect open wounds. Dangerous microorganisms such as E. Coli, Salmonella, and MRSA (Methicillin-resistant Staphylococcus aureus) are often present in biofilm and their spread to humans is quite dangerous. 

A clog in the shower drain

Hair, soap scum, calcium buildup, shampoos, and other substances can easily clog up the shower drain. They lead to a bad smell from the shower drain when they start decomposing.

The type of smell from this issue depends on the components in the clog. If the shower drain smells like rotten eggs, the clog would has lots of sulfur compounds from body and hair care products such as shampoos and lotions. If you have musty-smelling drains in your bathrooms, it’s a sign that the clog has mold growing on it. 

At times, the clog can be so severe that the shower drain doesn’t allow water to flow down the drain. This often leads to a flooding bathroom each time you take a shower. 

Leaking pipes

Leaks in your sewer pipes are a major cause of bad shower smells. The leaks allow sewer gases to enter the bathroom making for an unpleasant experience. 

Leaking sewer pipes can also lead to the spill of toilet wastes into the walls or the home and should thus be dealt with as soon as possible. A sewer smell from the shower drain can easily be a sign of leaking sewer pipes. 

If the bathroom smells like sewer after a shower, or there is a rotten smell lingering in the bathroom, have a plumber check the pipes since this is a serious issue. 

How to stop smelly drain odor

How to clean a smelly shower drain

You can get rid of smelly shower drains in the shower through the following solutions:

Fill the P-trap with water

The solution to a dry P-trap is simply filling it with water especially if the cause is evaporation. Pour about 4 cups of water into the shower drain then wait for an hour. If there is no water in the trap, it’s not evaporation but rather a leakage in the P-trap. 

For a leaking P-trap, call a plumber to seal or replace it with a new one. 

You can pour some cooking or mineral oil into the shower drain to prevent shower drain smells. Since oil evaporates slower than water, it’ll stay in place for longer. 

You can also prevent shower drain odor by simply running the shower every few days especially when the bathroom isn’t used frequently enough. This keeps water in the P-trap which in turn keeps sewer smells away. 

If there’s no P-trap in the shower drain, have a plumber install one for you. 

Clean the biofilm from the drain

The biofilm in the shower drain is cleaned in the following steps:

  1. Pour half a cup of baking soda into the shower drain. 
  2. Pour one cup of vinegar down the drain. 
  3. After 15 minutes, flush the shower drain with hot water

You need to scrub the inside of the shower drain with a toothbrush if there are stains of biofilm in it. 

You should also remove the strainer on the shower drain, and soak it in soapy water for half an hour before brushing the dirt off with a toothbrush. Rinse it afterward. 

You also clean biofilm from the shower drain by mixing bleach and water in equal parts and then pouring it down the drain. A smelly shower drain bleach solution will kill the bacteria and other dirt in the drain thus cleaning it up. A mold remover is also a great option for cleaning biofilm and killing mold from a shower drain

Unclog the shower drain

Unclog the shower drain with the following methods:

  1. Fill the shower drain with water then use a plunger to plunge it several times to dislodge the clog. Flush the shower drain with hot water afterward. 
  2. Insert a drain snake into the shower drain then crank its end to eat away at the clog. Flush the drain with hot water afterward. 
  3. Clear hair from the shower drain either by hand or using a hair-dissolving shower drain cleaner such as Green Gobbler Main Line Opener.
  4. Pour half a cup of baking soda into the drain followed by a cup of white vinegar. After 15 minutes, flush the drain with hot water. Baking soda and white vinegar also make a great shower drain deodorizer as they do away with the bad smells in it. 

You can also use a drain snake to unclog the drain. Simply insert it into the drain after removing the drain cover then crank the end in your hand as you push it further down the drain. It’ll eat away at the clog and unclog the drain. After that, flush the drain with hot water.

How to unclog a shower drain

Prevent the shower drain from clogging up by installing a hair catcher and washing it weekly with a mix of baking soda and white vinegar. You also prevent calcium buildup in the shower drain by changing to liquid soap as it doesn’t cause a lot of scum as bar soap does. Clogs in the shower drain can easily lead to drain worms which are a major nuisance. You should get rid of drain worms to fix this.

Fix leaking pipes

If you can reach and identify the leaks, fix them as required. You can simply replace the leaking pipes if the damage is too much. In some cases, you may need to call in an expert since pipes in the walls aren’t easy to reach and fix.

Call the plumber

The solution to some issues is simply calling for a plumber. For example, if you realize that the shower drain odor remedies above don’t solve the issue, call the plumber. Fixing leaking pipes is a complex task that is best left to the plumber to avoid further issues. 

Hydrogen sulfide gas (sewer smell), musty smells, and other unpleasant odors won’t be a problem having the knowledge above. Again, only handle what you can and leave the very complex tasks to the experts.

Frequently Asked Questions

Why does my shower drain smell like sewer?

A sewer-like smell from your shower drain may mean the P-trap has dried up. Since the P-trap traps sewer gasses from below, it loses its purpose when it dries up or leaks. Simply pour some water in it to return the seal.

How do you deodorize a smelly drain?

Pour half a cup of baking soda into the drain followed by a mixture of a cup of distilled white vinegar and a cup of boiling water. Cover the drain for 10 minutes with a piece of cloth then flush it with hot water.

Why does my drain smell so bad?

Biofilm, which smells like rotten eggs, can be found in drains, pipes, and other fixtures that can make your drain smell bad. Biofilm is mostly caused by bacteria feeding on human hair in the shower drain.

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