Woman spraying deoderizer in bathroom

Bathroom Smells Like Sewage? 7 Common Reasons Why

Got Nasty Sewer Odors in your Bathroom?

Man closing smelly toilet with foot
Bad bathroom smells can easily be sorted once you figure out what’s causing them!

If you’re hit with a wave of nausea every time you enter your bathroom, it’s time to tackle the root of the problem – nasty sewer odors. Trust us; you don’t want to let this issue fester. Not only does it make using your bathroom an unpleasant experience, but it could also spell trouble for your plumbing down the line. 

Get ready for solutions, in this article, we dive into the most common causes behind your bathroom’s unpleasant odors, and more important, how you can make them disappear for good. So, stop holding your nose and get ready to breathe easy when you next step into your bathroom!

Why Does My Bathroom Smell Like Sewage? Key Takeaways

  • A dry P-trap can cause bad odors. Simply pour water down the drain to refill the p-trap.
  • If the wax ring that seals the connection between your toilet and drainpipe is damaged then sewage gases can leak out. Replacing a damaged wax ring requires a plumber.
  • Gurgling sounds often indicate air trapped somewhere within your plumbing system, this needs to be vented out properly.
  • A common culprit for foul odor is a clogged-up shower drain, clear it out using baking soda, vinegar, and hot water.
  • If DIY fixes aren’t doing the trick or if your bathroom sewage odor is due to an issue with overflowing underground pipelines or a clogged vent pipe, call in a plumber as soon as possible. 
  • Be aware that sewer gases can contain hazardous compounds such as methane, so if you smell anything similar around your bathroom pipes, turn off your gas supply immediately and get in a professional for urgent inspection and repair. 
Make sure you know where your gas mains valve is in case it needs to be turned off immediately!

7 Causes of Sewer Smell & How to Fix Them

If you can pinpoint the cause of your sewer odor then you can likely fix it before it turns into a bigger and more costly issue. Whether you have a dried-out P-trap or a backed-up tank, you’re not alone in this smelly struggle, so let’s roll up those sleeves and solve this problem asap. 

1. Dry P-Trap

If you’ve ever rummaged about in an under-sink cupboard you’ve probably come across the P-trap. This is the U-shaped drainage pipe connected to the underside of your sink. Water sits in the u-bend creating a water seal across the opening, crucial for keeping smelly gas from seeping into your home. All it takes to resolve a dry P-Trap is pouring some new water down the drain to rebuild that protective barrier – problem solved!

plumbing trap under sink
Making sure there’s water in the bottom of the P-trap prevents odors from reaching your plughole.

2. Damaged Toilet

If you have a sewage smell near your toilet this may be caused by a damaged wax ring, the seal that connects your toilet to the drainpipe. This may have happened due to improper installation or simply just due to wear and tear. A damaged wax ring can cause sewage gas to leak into your bathroom instead of being properly routed through the piping ventilation system. Replacing a damaged wax ring requires removing and reinstalling a toilet which we recommend getting done by a plumber.

3. Gurgling or Bubbling Gases

Gurgling sounds often indicate trapped water or air within either the sewer line or in a plumbing vent. This is most likely caused by some sort of blockage that will need to be vented out properly. If not, unpleasant sewer smells can escape through the drains and into bathrooms or kitchens.

4. Clogged Shower Drain

Clogged drains are a common culprit for odious odors in your bathroom since hair, soap scum, skin cells, etc., easily accumulate in pipes over time and create blockages. When not regularly removed, this can lead to wastewater backing up and results in that offensive odor.

To remove such clogs first detach the shower drain then pour down some boiling water, then add baking soda followed by vinegar, leave for 10 to 15 minutes, then finally run hot water for several minutes to flush out the loosened debris.

Shower drain cover off and debris that was clogging drain set to the side
Use baking soda and vinegar to flush out debris that is out of hand reach.

5. Clogged Plumbing Vent Pipe

Vent pipes, located on the roof of a home, allow for sewer gases to naturally escape from your plumbing and simultaneously prevent any air vacuums from forming inside the pipes. Such a vacuum if formed could cause wastewater backups into your bathroom.

This may be caused by random outdoor debris or nests being built inside vents resulting in blockages and bad smells filtering back into your home through toilet and sink drains. If this is the case, this can only be resolved by using specialized equipment designed for this purpose.

6. Bacteria Build-Up

Bacteria are present everywhere, including in your plumbing system. Here, they play an important role in breaking down organic material in your sewage system making it easier for other downstream treatments (e.g., septic tanks) to work more effectively. Nevertheless, when bacteria levels become too high due to an imbalance in their ecosystem it will lead to bad smells in your bathrooms. 

For an obvious slimy orange-pink film on surfaces or in plug holes cleaning with some disinfectant or bleach will do the trick. 

7. Sewer System Backups or Full Septic Tank

The most serious reason for a sewage smell in your bathroom is due to some kind of sewer backup or overflow occurring somewhere within your property’s underground pipelines. If it happens frequently, then you likely have an issue with either your primary sewer line or septic tank. Trust me when I say that this isn’t a job for a DIY enthusiast, you need a professional for this task ASAP. Act now and save yourself some serious trouble and cash!

Septic system blocked with non-biodegradable items being unclogged
For septic system blockages, call in the professionals!

When to Call a Professional Plumber

Some plumbing problems such as hair-clogged shower drains or dirty p-traps can easily be fixed with a little DIY know-how and some household tools. However, sanitary systems are complex, and trying to fix the problem yourself might end up costing you more than you bargained for in the long run. If after some troubleshooting the problem persists or worsens, it may be time to call in the experts. Here are some instances when calling a plumber is probably your best bet:

1. Multiple Clogs

If your home has multiple drains all clogged up at once, there is likely a wider root issue at play. A skilled plumber will have the specialized tools and equipment needed to diagnose the cause and fix it. So, sit back, relax, and leave this headache-inducing task to the pros!

2. Old Pipes

Old pipe systems are more prone to problems such as leaks simply due to wear and tear over time from the constant use of running water through them. If this is the case in your home call an experienced plumber who can help determine whether new piping installations are needed.

Old, rusting drainage pipes taped up with blue tape to slow leaking
Rusted pipes are a common issue in older homes. Make sure to regularly inspect your pipes for signs of corrosion.

3. No Improvement With DIY Methods

If you’ve tried everything, but are still at a loss then it’s time to wave that white flag and get in touch with a professional. 

4. Gas Leaks

Sewer gases in your bathroom pipes, particularly methane, can pose a serious health risk if significant amounts are inhaled over time. If you catch a whiff of gas-like odors emanating from your bathroom turn off your gas supply immediately and call out a pro asap for inspection and repair work.

5. Water Damage Or Flooding

We’ve all had nightmares of water damage or flooding wreaking havoc in our homes. If you have this issue you need a professional plumber, and you need them fast! They’ll have the expertise to survey the damage and identify any underlying structural flaws.

Water leak from room above causing water damage on the ceiling
When your ceiling looks like this, you best get a plumber in before any more damage is caused!

Bathroom Smells Like Sewage? 

Don’t let that pesky sewage stench get the best of you! Armed with the right information and equipment, fixing the root cause of bathroom foul odors can be an absolute breeze. If after troubleshooting the 7 most common causes in our list you find yourself in over your head or feel uncertain about handling the issue, do yourself a favor and call in a trusted plumber instead.

If you found this article helpful, please share on social media or leave a comment below! Let’s help our fellow homeowners defeat offensive bathroom stenches!

About the author

An accomplished plumber with more than 15 years of experience in the industry, David "Fitz" Fitzgerald began as an apprentice and steadily worked his way up to become a fully licensed and certified master plumber.

With extensive training in all aspects of plumbing. David is well-versed in the installation, repair, and maintenance of plumbing systems, including pipes, fixtures, and appliances, and is able to troubleshoot and solve even the most complex plumbing issues.

He loves to share his wealth of knowledge and looks forward to engaging with the community here on No Hassle Plumbing.

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