Sewer Gas Smell in Bathroom: How to Identify & Get Rid of Odors

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Unpleasant odors may emanate from a bathroom drain.
Image Credit: Krzysztof Winnik/iStock/GettyImages

When you have a sewer gas smell in the bathroom, it's not enough to leave the fan on and blast things with air fresheners. You have to solve the problem and find the source of the odor. Often, it's nothing too serious, but if DIY remedies don't do the trick, you'll need to call a plumber. Don't ignore sewer gas smells, though, because the gases can affect your health, and it could suggest something more dire, like blockages causing a sewage leak or backup.

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It might take a couple days for the odors to become prevalent enough for concern, but once they have, take immediate action. As the gases build, health hazards increase. Long exposure can cause dizziness, nauseousness, drowsiness, headaches and even loss of consciousness, and these symptoms can be worse in children or the elderly.

Gases are involved, and extreme buildup can be combustible. Among the potential gases are methane and hydrogen sulfide. If you smell a whiff of rotten eggs, the gases can be both flammable and toxic. Airborne pathogens are possible as well, so it's wise to wear a painter's mask if you're tackling this issue.

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Plus, there's also the danger that the smells are caused by an actual sewage backup, which can turn into a devastating and costly issue, such as needing to replace a sewer line, if it persists and worsens.

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There are multiple things that can cause a sewer smell in your bathroom, and the remedy is dependent on what's causing the smell or from where it's coming. These remedies are by no means exhaustive, and calling a plumber should always be on your list, as this is one problem that needs to be solved sooner than later.

Warning

Exposure to sewer gases can lead to health problems, like nausea, headache, breathing issues and more.

What’s That Sewer Gas Smell?

You know what goes down your drain pipes, and you know it's headed to sewer lines. It's a testament to modern plumbing that sinister sewage smells in the bathroom are uncommon, but when they happen, it's often something as simple as a dry P-trap or a clog. Often, it's a buildup of bacteria and gunk since debris stuck in the pipes inevitably rots and produces methane gas, a culprit in sewage gas odors.

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If you can discern from where the bad odor is emanating, then that's a head start and where you should focus your efforts. Don't presume it's from the toilet. These odors can come from anything connected to your home's water system, including the washing machine and shower. How to get rid of a sewer smell in the bathroom depends on the causes. In California, for instance, you may want to investigate whether an earthquake has caused damage to your home's pipes.

Shower Drain Solutions

Shower drains can have funky odors from grime and buildup over time, especially for hard-working showers serving multiple people. Organic matter, whether it's scum from products used or long hair causing a blockage, always rots eventually, but a good cleaning should resolve the stench. If you're unsure about proceeding, it helps to know your shower drain's parts.

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  1. Expose the drain by removing the shower drain cover. You may need a screwdriver for this.

  2. Flush the drain pipe. Heat 5 to 10 quarts of water to 150 degrees Fahrenheit; do not use boiling water in large quantities or you could damage the pipes. Pour this down the drain all in one go.

  3. Pour 1 cup of distilled white vinegar down the drain followed by 1/2 cup of baking soda. Let it sit for two hours.

  4. After two hours, pour another gallon of hot water down the drain. Use a brush to scour the parts of the drain you can reach and then run the tap for a couple minutes to rinse the pipe. This should both clean out the pipe and refill the P-trap.

Remedying a Smelly Sink

Anywhere you have a drainage pipe, a dry P-trap could be the problem, and to solve it, it's just a matter of pouring water or running the taps long enough so the P-trap can fill with water again. Drain pipe debris could be a problem in the sink drain too, and the shower drain method works for this as well. Just use 1 gallon of water heated to 150 degrees Fahrenheit to pour down the drain followed by another gallon of hot water after two hours.

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The problem may be that the overflow is coated in mildew or grime, so a DIY solution can save the day there too.

  1. Use a bottle brush to scrub the accessible overflow of any debris.

  2. Mix 1 cup of warm water with 1 cup of chlorine bleach and scrub the overflow area with this solution. Then, pour what's left down the overflow.

Solving Stinky Toilets

Toilets are mounted onto the floor drain with two seals, including a wax ring. When you have a cracked or broken seal, the bad smell in the bathroom may be from the wastewater penetrating the seal and accumulating around the base of the toilet. A good indication of this problem is if you've noticed the toilet bowl isn't filling with water to the same level it once did. Also, wax seals can easily break if your toilet is wobbly for any reason.

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Broken seals may require a more intensive repair and are a good reason for a plumber. If you're toilet-plumbing savvy and want to give it a go yourself, you'll need some caulking. It helps to understand the essentials with toilets and their plumbing.

  1. Look for damage elsewhere; seals can be caulked, but cracked toilets will need repair or replacement.

  2. If the toilet looks fine but seals are cracked, apply caulk around the seals.

  3. Caulk the bolt holes where they secure to the ground.

If you're successful, the odors will vanish soon. If there was other damage, the toilet may need to be replaced. Any cracks or signs of physical damage could well be the cause of your stinky situation. Maybe someone snaked the drain with too much aggression, in which case pipes can crack, and sewage buildup ensues. In these instances, a toilet replacement or plumber's visit is wise.

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If other toilet fixes haven't worked and the odor has always existed but is getting worse, it may be a vent pipe that was improperly installed or poorly cut. Simply put, vent pipe remedying is a job for a plumber.

Things to Avoid

Boiling water is often suggested on DIY sites as an easy fix, but it can make things worse if pipes are brittle or old, as the excess heat can crack pipes or break seals. Instead, use hot water, not boiling.

Store-bought solutions for clearing clogged pipes are popular, but they are toxic products that can mix with other cleaners to create deadly gases. If it's not somehow fully flushed from the plumbing system, it can corrode or damage the pipes. They are seldom a permanent fix for clogs, they pose an environmental hazard and they're likely not the solution to your foul odor issues. There are several chemicals that can melt or damage your PVC pipes and avoiding them entirely is wise.

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references

Steffani Cameron is the daughter of a realtor and interior decorator mother and a home contractor father. Steffani is a professional writer with over five years' experience writing about the home for BuildDirect and Bob Vila. Raised with a mad love for decorating, Steffani gave up her Art Deco apartment to travel and work remotely for five years. She's in love with experiencing traditional decor around the world, including stays in Thai teak plantations on the Mekong River and cave homes in Turkey.

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