Does your toilet smell bad even after it has been flushed? You might clean the bathroom and the toilet only to find that the toilet still smells bad. Why is this the case, and what can be done about it? You might be surprised at what can cause the smell of sewer gas to seep into your toilet and living space.

Possible Causes of a Smelly Toilet

The truth is that your toilet is a private space and you’d really rather not be reminded of what goes on in there. When your toilet smells, it can affect your family and will even draw the attention of visitors to your home. So, what causes a smelly toilet? Consider the following:

1. A Low Water Level

When the water level in the toilet bowl gets too low, it can actually allow smelly sewer gases to seep out and escape. Sometimes, this happens because the toilet piping is partially blocked and the water doesn’t fill the bowl all the way to where it needs to be. It may also happen if an errant dog drinks water right out of the toilet bowl regularly while you’re at work. For an easy fix, if you have dogs, try keeping the toilet lid closed when you’re not home.

2. Evaporation

If you have a second or third toilet in your home that doesn’t get used a lot, the water will evaporate and will get low, causing the sewer gases to escape. The easy way to fix this is to make sure that you keep those extra toilets flushed regularly so the water stays at a consistent level in the bowl.

3. The Wax Seal

Around the base of every toilet is a waxed ring that keeps the moisture from getting into the room. When this wax is damaged or old, it can allow sewer gases to escape. This may especially be the case if your toilet is so old that it moves when you sit on it. The movement of the toilet combined with the damaged seal means that gas will escape where you don’t want it. The easy solution is to have a plumber check it out and install a new wax seal. We recommend:

4. Bacterial Growth

We all know that some pretty nasty bacteria resides in sewer pipes, but most of the time this bacteria remains in those pipes.

The problem is that sometimes colonies of bacteria will make it all the way up into your toilet bowl and under the rim. This is where they’ll start to grow and grow. As this happens, foul gases are released. The best way to fix this is to put some bleach into the cistern and flush it several times to make sure the bleached water flushes all the way around the rim. We recommend:

5. A Crack in the Toilet

It’s not uncommon for there to be a small hairline crack in the toilet bowl that results in the water levels getting too low on a regular basis. This can even be caused when a plumber uses a snake to unclog drains. In this case, the water will leak out slowly and get into the drain and the subfloor area. It may even cause more damage, so it’s wise to have it assessed as soon as possible by a professional plumber. It’s possible that you’ll need a new toilet.

6. Vents That Are Clogged up

Bathrooms and toilets have drain vents that keep them well ventilated. This also allows bad smells to escape to the outside. When these vents are all clogged up and blocked, it can lead to bad smells forming in the immediate area.

This clogging can happen for any of the following reasons:

  • Blocked by a dead bird, bird nest, or other animals
  • Clogged up by grease, soap scum, or frost that has formed in cold climates

If this has happened, the best way to deal with it is to call a plumber who can assess the state of the vents and use their own tools to unclog them.


The toilet is a private area and no one really wants to be reminded of what happens in there. This is why so many people use scents to mask any smells. Unfortunately, there are a number of good reasons why sewer gases can escape into the room and cause foul smells. Fortunately, they can all be solved.