How to Fix a Smelly Shower Drain: 5 Ways to Keep Drains Smelling Fresh

We’ve all been there — stepping into the shower, looking forward to unwinding after a hard day, only to have our nostrils assaulted by unpleasant odors wafting up from the shower’s drain. If you’ve asked yourself the question, "Why does my shower drain smell?" you’re not alone.

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Smelly shower drains are a common, stinky issue. But you might be glad to know there’s an easy fix you can do with a little know-how.

Why Your Shower Drain Smells So Bad

Here are the most common reasons odors might be escaping through your shower drain and what you can do about it.

Dry P-Trap

Reason: The P-trap is a curved section of pipe designed to hold water, creating a barrier that prevents sewer gasses from entering your home. Those unpleasant odors will escape through the drain if the P-trap dries out. The most common cause is evaporation, especially in winter or if your climate is dry. Infrequent use is another reason, as is something in the pipe absorbing the water, such as balls of hair.

Solution: Thankfully, there’s a simple fix for this problem. Pour a gallon of water down the drain to refill the P-trap and restore the barrier.

Clogged Drain

Reason: Over time, debris can accumulate in the drain pipe, causing a clog that traps water and organic matter. When this matter begins to decompose, it releases foul odors. The type of debris causing the problem typically includes hair shedding while you shower and soap scum, such as the residue from shampoo. If you live in an area with hard water, minerals such as magnesium and calcium might gradually accumulate to create a barrier. Fortunately, this is a problem you may be able to fix without a professional’s help.

Solution: Remove the drain cover (usually by twisting it counterclockwise) and clean it thoroughly with hot, soapy water. You can also use a baking soda and vinegar solution. Pour half a cup of baking soda down the drain followed by half a cup of white vinegar. The mixture will fizz and help break down the buildup. Let it sit for 15 minutes, then flush with hot water. If this doesn’t work, it’s time to call a professional plumber.

Sewer Gas Leak

Reason: If the smell from your shower drain reminds you of sewage or rotten eggs, it could be a more serious issue with your plumbing system. Sewer gases can enter through cracks or leaks in the drain pipes, allowing the unpleasant odors to permeate your bathroom. Fats and oils cooling inside the pipe before they’re expelled can be a reason for this problem. Foreign objects, such as feminine hygiene products, diapers and wipes, can also cause this issue. The blockage might even be a tree root intruding into the pipe.

Solution: In this case, it's best to contact a licensed plumber to inspect and repair any leaks or damage in the pipes. Never attempt DIY where sewer gases are concerned, as they primarily consist of methane and hydrogen sulfide, which are highly flammable.

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Biofilm Buildup

Reason: Biofilm is a slimy layer of bacteria, fungi and other microorganisms that can accumulate inside drain pipes, especially in areas with standing water. This buildup can produce a musty, unpleasant odor that will weave through the system, emerging from your shower’s drain. Certain pipe materials, such as cast iron or older PVC pipes, can be more prone to biofilm buildup due to their rough surfaces and potential for corrosion. If your home has older pipes, you may want to consider replacing them to prevent the issue from recurring.

Solution: To combat biofilm, remove the drain cover and use a drain snake or other tool to scrape away any visible buildup. Then, pour a mixture of vinegar and baking soda down the drain, followed by boiling water.

Ventilation Issues

Reason: Vent pipes on your roof can easily be blocked by various types of debris, such as leaves and even animal nests. In some older homes, the vent pipes may not be sized correctly for the plumbing system, being too small to provide sufficient ventilation. Although less common, negative air pressure within the home can cause sewer gasses to be drawn back in through the drains. This can happen if your home is tightly sealed and doesn't have enough air intake or if powerful exhaust fans or appliances create a strong negative pressure.

Solution: If you suspect a ventilation issue, it's best to call a professional plumber to inspect and clear any blockages in the vent pipes.

By understanding the common causes of smelly shower drains and implementing these simple solutions, you can keep your shower smelling fresh and welcoming. Remember, if the problem seems beyond your DIY skills or involves potential plumbing system damage, don't hesitate to call a professional plumber for assistance.

Does your shower drain smell as unpleasant as a dumpster in a heat wave? Now you know why it smells, how to fix it and when it’s better to call a pro.