Keeping your bathroom free from disagreeable odours is a significant concern for most homeowners.

Most bad smells can be managed by using air fresheners, but it would be better to purchase products labelled as odour eliminators rather than buying air fresheners. Air fresheners only mask the smell, and when the odour is too pungent, it may overpower the scent; while odour eliminators work to neutralize foul odours.

There are many different odour eliminators available, and it would be best to choose one with the best reviews.

Maintaining a clean, fresh smelling bathroom can be quite the chore, but the benefits outweigh the hard work. It can be a source of pride if you do indeed take care of your bathroom or it can also become a major embarrassment if you have guests.

If you still notice a foul odour even after cleaning your bathroom thoroughly, then there might be a slightly bigger problem. There are quite a few factors to take a look at when looking for the cause of the sewage smell in your bathroom. You don’t have to worry we will be tackling each one.

Eliminating the sewage smell in your bathroom


To help solve this problem it would be best to understand how your bathroom plumbing works. We have all spent countless hours sitting on our thrones staring at the piping under the sink and not caring how it all works. Now is your chance to find out.

There should be a U-shaped pipe that is connected from your sinks drain to a larger wastewater pipe in the wall. Your baths drain and toilet is also connected to this larger wastewater pipe which has two ends.

One end leads up to the roof, allowing fresh air in and letting any septic or sewer gases out in the open air. The other end runs all the way to the sewer or your septic system. It is a relatively straightforward design but this has allowed us the innovation of indoor plumbing which we enjoy to this day.

The water main is of course connected to your faucets, showers and any fixture requiring fresh water; while the wastewater pipe is again connected to the sewer and has a vent to the roof. The U shaped pipe found under your drains, sinks, and toilets trap water to create a water barrier preventing awful smelling gas from seeping into your home.

Probable reasons for the Sewer Smell

  • Dry trap
  • Overflow hole
  • Clogged Drains
  • Toilet ring
  • Leaky pipes

Also, in extreme cases, the grout and tiles in your bathroom might have collected bacteria over the years causing the smell. Knowing how to clean bathroom grout would then be very beneficial.

Run water/P-trap

One of the most common factors to the sewage smell in your bathroom may also be the easiest one to resolve. This could just have been caused by lack of use of that particular bathroom. For bathrooms that incur typical usage, a water barrier would form in the pipe under the drains.

We are all familiar with u shaped pipe under the sink, this is technically called the P-trap. It was designed that was to trap water in u shaped portion of the pipe to prevent bad smells from the septic systems or sewers to creep up and out of the drains.

People assume that the primary function of this u shaped pipe is for when our jewellery or valuables fall inside the drain. Its main purpose is instead to trap water and form a water barrier against sewer smells.

When a bathroom is not used very often the water that forms in the P-trap evaporates over time. This is when foul-smelling gas from the sewer or septic system escape into your bathroom.

Try running water in both the shower or tub as well as the sink and this should block any foul odours from seeping into your home. Make sure your toilet also fills with water when you flush it or else this could be the culprit.

Do this at least once a week. Include this in your weekly bathroom maintenance schedule and add a spoon of oil to prevent the water from evaporating too quickly. If this did the trick and you no longer notice rotten smells coming from your bathroom then congratulations on the easy fix.

Overflow hole

After doing the above procedure and for some reason the odour persists then try checking the overflow hole in your sink. This is the hole or slit customarily located below the faucet and above the drain.

The purpose of which is to redirect any water that seeks to overflow the basin of your sink.  Sometimes this hole accumulates mould, mildew, and slime since it is rarely cleaned. This could be the where the bad smell is coming from.

It would be best to get it cleaned right away and include this in the weekly maintenance cleaning of your bathroom.

Try cleaning it with a sponge using bleach and an old toothbrush if the hole is too small for the sponge to handle. While cleaning the bleach and slime would spill on the floor, make sure to use a mop soaked in bleach to wipe that mess away.

Check for Clogs

All the foreign materials that get flushed down the drain like hairs, old biological material, gunk, debris getting stuck in the pipes could cause unpleasant odours. There are heavy duty drain cleaners that you can purchase and you can also try more environmentally friendly options.

Drain cleaners are composed of harsh chemicals, so it is something to keep in mind if you will be flushing this out onto the environment and not a septic tank.

Just pour the drain cleaner and wait the required time to allow the chemical mixture to work and break down any blockage accumulated over time.

Drain cleaners have the sole purpose of destroying any foreign materials that may get lodged inside pipes and would be the best option for very tough clogs. Pour a gallon of hot water down the pipes to flush down all debris and clear any sludge blockage.

Another option would be to go natural and just use baking soda and vinegar to unclog drains. Just pour half a cup of baking soda, a cup of vinegar into your drains, let it sit for 30 minutes then pour a gallon of hot water to clear any blockages in your pipes.

It would actually be an excellent practice to keep your pipes clean and for preventive maintenance as well. This ritual would help clear any type of buildup in your pipes and make sure you won’t have to deal with any clogged drains.

Clearing your drains of any mildew, scum and any foreign materials should have fixed the problem if indeed this was the reason; If not the last thing we can check is for any leaky pipes.

Toilet Wax ring and seals

A visible indicator that the toilet wax ring is broken is if the toilet wobbles. This would be the cause of the sewer smell, not only is it unsanitary it is unsafe as well.

The toilet wax rings the main purpose is to seal the toilet to the main waste pipe flange in the floor. Again if your toilet wobbles this means the seal is broken. It may be due to wear and tear, or it is possible it was not installed correctly.

Toilet seals work by sealing the ceramic underside of your toilet to the toilet mounting flange and the main waste pipe together. There are several different toilet seals. The traditional wax ring toilet seal, a waxless toilet gasket or a toilet mounting-flange and toilet seal wax ring combination package.

They are all available at your local hardware and if you are not sure which one your toilet needs it would be best to consult a professional.

Leaky Pipes

This could be difficult to fix yourself. The best thing you can do is check on all the pipes that are visible in your bathroom and throughout your home and set any leaks by applying PVC tape to minor leaks. For more severe leaks there are patch kits available at the hardware store. Most patch kits contain a rubber pad to cover the hole and metal plates that press the rubber patch sealing the hole.

If the leak is not visible to you, it is best to get a licensed, insured plumber. It is now time to get the professionals to fix the problem for you.


Going through this checklist to find the cause of the awful stench yourself should help you fix your sewage smell in the bathroom.

In case you need the services of a professional plumber please do a quick search online for the most recommended professional. Make sure to hire a licensed and insured plumber to protect yourself and your property from any unexpected damages.

Photo by Karla Alexander on Unsplash

Hi there! I’m Guy, the guy behind Guy About Home (that’s a lot of guy’s). I’m just your average guy (ok, I’ll stop) living in the USA who is really interested in making and doing.