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What Makes My Bathroom Smell Like Sewer?

Wondering what's making your bathroom smell like a sewer? Read this post for the most common causes of a sewage smell in your bathroom and how to fix it.

white bathroom with smelling oils

If you’ve ever experienced an unpleasant odor in your bathroom, you know how horrible and embarrassing it can be, especially when you have guests over. Even worse is when your bathroom smells like sewer. 

But what makes a bathroom smell like sewer in the first place?

In general, bathrooms smell like a sewer from clogged drains, leaky pipes, a loose toilet wax ring, a build-up of bacteria, to a blockage in the sewer system. 

Luckily there are some pretty simple ways to figure out how to detect that bad smell in your bathroom and even simpler solutions to making it smell better. 

Keep reading to find the cause of your stinky bathroom and what you can do about it.

Table of Contents

What Causes a Bathroom to Smell?

Picture of a clogged drain under a bathroom sink.

A sewer smell in the bathroom is normally caused by something small like a clog in the shower drain or a dry P-trap under your sink. In other cases, the cause can be a bigger issue such as a backed-up sewer line that needs professional attention.

Sewer gasses are a byproduct of septic systems and when pipes leak or become blocked, these gasses flow back into the bathroom instead of venting outside.

It’s worth mentioning that when it comes to a sewer smell, it’s important to remedy it as soon as possible since the hydrogen sulfide in sewer gasses can be harmful to your health and may even cause an explosion if bad enough.

Let’s go over what usually causes these offensive and embarrassing odors.

Clogged Drains and Pipes

One of the most common reasons a bathroom smells like a sewer is because of a clogged drain or pipe. 

Usually, it’s as simple as the shower or sink drain having a build-up of soap scum, hair, and skin debris. 

Likewise, the toilet can naturally become clogged over time from normal use or because an object has gotten into its plumbing system.

Dry P-Trap

The P-trap (which is the U-shaped pipe under your sink) is designed to keep a small amount of water beneath the drain to prevent sewage gas from reaching the room. 

When the sink isn’t used frequently enough, the water in the P-trap evaporates and thus releases these sewer gasses into the air. 

Loose or Damaged Wax Ring

A toilet wax ring is supposed to have an airtight seal to keep gasses contained, but can become loose or damaged over time.

If your toilet’s wax ring is loose, sewer glasses may be leaking out through the gaps. 

Compromised Vent Pipes

Vent pipes are meant to take away the toxic gasses from your sewage system and give everything a chance to breathe. 

However, when they’re compromised due to improper installation, a crack, or a clog, they can’t effectively vent the gasses from the air. This leads to the terrible odor being transported back to your bathroom.

Bacteria in Water Heater or Toilet

A buildup of bacteria can also be the culprit of the sewer smell in your bathroom. 

Sometimes bacteria can build up in your water heater when it isn’t used often or set to a high enough temperature. 

Odor-causing bacteria can even build up within the toilet itself, especially in warm seasons when bacteria grows at a much higher rate.

Full Septic Tank

If you have a septic tank connected to the rest of your sewage system, it may be full and forcing sewage gasses up into your bathroom. 

A septic tank can overfill for a number of reasons and can cause slow drainage in your sink and tub, as well.

Blockages in the Main Sewer Line

A blockage in the main sewer line can be the most urgent and expensive reason why your bathroom smells like sewage.

When there is damage to your sewer’s main pipes, it can cause the gasses from all of the waste to backflow into your home because it simply has no other way to go. 

[shutterstock photo: https://www.shutterstock.com/image-vector/house-sewage-system-pipes-sink-bath-1296770746|

Why Does My Bathroom Fan Smell?

Man taking apart a bathroom fan.

Do you have a sewer smell when the bathroom fan is on? This is likely caused by the gasses and odors being circulated in the room when the fan is running, not because there’s something horribly wrong with your exhaust fan. 

When your bathroom fan is running, it’s simply pulling out the odors from the room and trying to get rid of them, regardless of what is actually causing them to begin with.

How to Make a Bathroom Smell Good

There are many ways to make a bathroom smell good, such as candles or room sprays. 

While they may smell fantastic and work in normal circumstances, they’ll only be masking the real cause of that terrible sewer smell in your bathroom until you fix the real issue.

Fix the Problem First (and Fast)

Before you focus on making your bathroom smell good, make sure you’ve figured out what’s causing the smell by trying some or all of the following solutions. 

Unclog the drains and pipes: 

You can clear clogs and dissolve debris with tools like a drain snake, homemade cleaning solutions like baking soda and vinegar, or specialty products that are designed to unclog drains.

Run water through the P-trap:

If you haven’t used the sink in a while, simply let the water run for a couple of minutes so that the P-trap has water again. 

Replace the wax ring:

When your wax ring is dry, cracked, or loose, it should be replaced. Luckily this is a relatively easy and cheap fix.

Inspect pipes and vents: 

If you have a basic understanding of the plumbing within your sewer system you can inspect the pipes and vents for any signs of damage or improper installation. 

Kill bacteria in the water heater or toilet:

You’ll want to consult the manual or a plumber before attempting to kill the bacteria in your water heater so you don’t damage it or contaminate your water. 

Taking care of the bacteria in the toilet is pretty easy, though. You can put a small amount of bleach in the toilet bowl, scrub, and let it sit before flushing. 

It’s also a good idea to thoroughly disinfect the toilet tank and all of its parts, as this is another common place for bacteria to build up. Make sure you use disinfectant products that are designed for the job and are septic safe. 

Empty the septic tank:

Many people empty their septic tank themselves, while others hire a professional to take care of it. Either way, if your septic tank is full it needs to be dealt with.

If you plan to handle your septic tank yourself, be sure to use proper handling guidelines for dealing with a part of the sewage system.

Consult a plumber:

When you can’t (or don’t want to) figure out how to detect that bad smell in your bathroom, call a plumber to take over the job.

How to Make a Bathroom Smell Like a Spa

Double bathroom sink with jar of good smelling oils.

Once you’ve taken care of whatever is causing the offensive odor, you can use the following tips for making your bathroom smell like a spa so it’s the relaxing space it’s supposed to be.

  • Make sure the exhaust fan is clean
  • Use an air purifier and/or essential oil diffuser
  • Only use low-odor cleaners
  • Empty hampers and remove wet towels
  • Place fresh flowers or plants in the room
  • Use a wax melter
  • Light a candle

How Long Does It Take for a Bathroom to Stop Smelling?

Depending on why your bathroom smells in the first place, it will likely smell better the same day of resolving the problem. 

In some cases, it may take a couple of days to fully air out, though. You can open the windows and turn on the exhaust fan to speed things up or ask your plumber for their recommendations.

When You Can’t Get Rid of the Smell in Your Bathroom

When you’ve used your detective and DIY plumbing skills and you still can’t get rid of the smell in your bathroom, it’s time to call in a professional plumber. 

A stubborn sewage smell is usually a sign that a bigger problem is to blame, which may or may not be an easy fix.

Some things you just can’t DIY and if the sewage smell persists or comes and goes over time, it’s important that you contact a specialist right away. 

By putting it off, you risk harming your health from breathing in the sewage gasses or further worsening the problem. 

More damage can take place the longer you wait, which means it can also become more costly to fix. 

Final Thoughts

If you walk into your bathroom and can’t help but think why does my bathroom have a weird smell? you need to inspect some things. 

Sewage systems are complex and what makes a bathroom smell like a sewer can vary from a simple clogged drain to an entire main sewer line being blocked. 

No matter what the cause is, it’s worth figuring out. Your nose and guests will thank you for it.