Fast Plumbing Answers: Bathroom Smells Like Sewage?

You’re here because there’s an unpleasant odor in your bathroom. The first thing you need to do is identify exactly where it’s coming from, then look for visible water leaks. We know it’s gross — but if your bathroom smells like sewage, you need to diagnose the issue quickly.

Let’s get you some answers in 2 minutes or less.

We’re Mother, a Dallas-Fort Worth plumbing company that provides dependable, hassle-free modern plumbing for homeowners who value quality. If you ever need us, we’re here to provide you long-term plumbing solutions that last. 

Do 3 Things Right Now If Your Bathroom Smells Like Sewage

If there’s a sewer gas smell or unpleasant odor in your bathroom, do these 3 things right away and then keep reading:

1. Ventilate your bathroom. Open the window and use exhaust fans to air out your bathroom. If there’s a sewer gas issue, you need fresh air in your house immediately.
2. Check for leaks. Look for visible signs of water around the base of your toilet, the base of your tub, underneath your sink, and coming out of all your bathroom drains. Don’t touch any water you find — it’s probably wastewater.
3. Do a quick sniff test. Try your best to pinpoint a specific area where the smell is strongest. You’ll narrow down the potential culprits and have a more informed conversation with your plumber.

We strongly suggest ventilating the space before following any other steps. You’ll limit exposure to toxic sewer fumes and any potential bacteria. 

Why Your Bathroom Smells So Bad: The Fast Answer

There are 4 primary reasons why there’s a sewage smell in your bathroom. If you’ve identified where the smell is worst, use that information to guide your way through this section.

Clogged drain

The most common reason for sewer smells in your bathroom is a clogged drain. If you can identify the source of the smell, here are the likely culprits for specific bathroom drain clogs:

• Sink clog: hair, soap scum, shaving cream and mineral deposits from hard water
• Toilet clog: toilet paper, hygiene products, toilet seat covers and non-flushable items
• Tub clog: hair, soap scum, pet hair, bath bombs and hard water deposits

Dried out p-trap

The p-trap is a u-shaped pipe that holds a smell amount of water to prevent sewer gases from entering your home. They exist under your sink and tub, and much less frequently under your toilet.

If you don’t use a bathroom fixture often enough, the water in your p-trap evaporates. This allows sewer gas to escape up your drain and into your bathroom.

Toilet leaking at base

Your toilet has a wax ring around the base. This wax ring creates a seal between your toilet and the floor, which prevents wastewater leaks and odors from leaking out.

If your wax ring is improperly installed, worn out or cracked, it’s easy for water and sewer smells to exit through those gaps. If you have a wobbly toilet, or notice leakage while your bowl flushes and refills, this is why your bathroom smells so bad.

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Leaky drain pipe

Drain pipe leaks and cracks are tough to spot, because they’re installed to be hidden from view. Most bathroom drain pipe leaks are under your floor or in your walls.

Look for wet, damp or soft spots in the floor or walls around your sink, toilet, tub and shower head. If you find any, this is likely the cause of the odor in your bathroom.

More Fast Plumbing Answers About Drain Clogs

Bathtub and toilet clogged at the same time?

Toilet keeps overflowing after your flush?

Drain not working (even after plunging and Drano)?‍

Toilet always clogging?

3 More Serious (But Less Common) Smelly Bathroom Culprits

If you can’t locate a visible leak or identify any surface clogs or blockages, there may be an issue in your main sewer line or with a drain vent on your roof.

Vent pipe blockage

The branch drain lines in your bathroom are connected to vents on your roof. If one of these vents is blocked by leaves, debris or animal nests, it creates a vacuum in your drain pipe.

These vacuums force wastewater and noxious sewer gases back into your home and out of your drains.

Sewer drain disconnection

If you live in a pier and beam home, a disconnected sewer drain causes wastewater to pour into your crawlspace. This nasty situation causes sewage to accumulate and odors to waft back up your drains into the bathroom.

Sewer line clogs and breaks

A sewer line clog or break is most likely if you have multiple slow drains in your bathroom, gurgling sounds in multiple fixtures, or a pungent odor emanating from multiple drains.

If you notice bad smells or backups around multiple bathroom fixtures, contact a plumber immediately to conduct a non-invasive sewer camera inspection.

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A Simple Solution For Your Specific Problem

There are several key reasons why you have a sewer gas smell in your bathroom. Let’s pair your specific issue with the best possible solution to the problem, so you can fix it as quickly as possible.

If you have a clogged drain, don’t use a chemical drain cleaner OR baking soda and vinegar. Both of these solutions can damage your pipes. Use an enzyme drain cleaner like Endure. If that doesn’t clear the blockage, call a plumber for drain augering.

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If you have a dry p-trap, you should be able to fix the issue by running water down the affected drain for a few minutes. If the p-trap is excessively dry, apply a small amount of mineral oil down the drain to slow down evaporation.

If your toilet’s leaking at the base, don’t DIY your wax ring replacement unless you’re a professional plumber. You risk coming in contact with wastewater, sewage and bacteria. Call a plumber to fix that wobbly toilet instead.

If you have a leaky drain pipe, call a plumber. Ask for non-invasive leak detection services, like acoustic or electronic leak detection. You’ll find the source of the smell without cutting open any walls or floors.

If you suspect a vent blockage, carefully check your roof for visible blockages. If you can safely remove them, do so. If you can’t, call a licensed plumber to access the vent.

If you suspect a sewer line issue, call a licensed plumbing expert that offers sewer video camera inspections. You’ll diagnose the issue before investing a dime in sewer line repairs.

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