Do Composting Toilets Smell? [Definitive Guide for 2023]

So, you might be considering getting a composting toilet, so you’re evaluating its potential downsides. If you’re someone who like a clean environment that always smells optimal, the question, do composting toilets smell probably pops into your head.

Well, in this article, we’ll cover EVERYTHING you need to know about this.

Composting toilets do not smell if properly maintained and set up. A correctly set up composting toilet includes the right filler, liquid, starter, and systems. If you do not properly set up and maintain your toilet, whether you have a regular one or compost, it will stink up. 

Let’s dive into more detail.

Normally, composting toilets should not smell – if set up right, composting toilets can actually smell better when you’re finished.

You’ll need to make sure your bathroom has proper ventilation, enough moisture, a great seal, and there is enough filler.

On top of that, you’ll also need to empty your toilet frequently. Below we have some great tips on how to set up and maintain your toilet.

How to Keep Composting Toilets Smelling Fresh

So, how do you set up and maintain your composting toilet so that it doesn’t smell? Well, that’s what we’ll cover right now.

Large Tank & Negative Pressure

So, how do you make your toilet smell great all the time? The trick is to have an extra large tank with a small fan in it – also known as negative pressure. Negative pressure can help vent odors and keep the systems operating smoothly.

As soon as you open the toilet lid, the air will be pulled into the tank and sent outside. Having just these two things will do you wonders.


Having great ventilation is also important. Good ventilation can be as simple as having an exhaust fan. Having a window also helps.


You’ll want to make sure you have a good amount of moisture. 

There are a few ways to add moisture to your composting toilet. One way is to add a layer of peat moss or coco coir to the bottom of the toilet before adding your composting material. 

You can also add a layer of damp newspaper or cardboard to the top of the composting material. Finally, you can mist the composting material with water every few days.


A compost starter is a bacteria or fungi culture that is added to organic waste to help speed up the composting process.

The starter helps break down the organic matter more quickly, making it richer in nutrients and better for your plants.


Next, empty your toilet every two months if it’s one person using it all the time. If two people are using it full-time, you should empty it every three weeks to one month. 

Families will most likely need to empty their toilets every week or so. You can empty it in your personal composting system for fertilizer while helping reduce greenhouse emissions.

Here’s a video with more tips:


Here are some related questions to ‘do composting toilets smell’ that I thought may be relevant.

Can a Portable Toilet Be Used as a Composting Toilet?

A portable toilet can be used as a composting toilet if it is large enough and has a ventilated lid. The toilet should be placed in a sunny location on top of a layer of absorbent material, such as sawdust, wood chips, or straw.

These will probably smell more because negative pressure and a large tank are difficult to do.

What Size Should My Composting Toilet Be?

The best size for a composting toilet is a 34 gallon unit. This size is large enough to accommodate a family of four, while still being small enough to fit in a typical bathroom.

This size is also easy to maintain and empty, making it the ideal choice for most households.

Final Words

So, getting back to the main point. Do composting toilets smell? Composting toilets aren’t supposed to smell if you set them up correctly. Setting them up includes:

  • Having a large tank
  • Having a fan in your tank for negative pressure
  • Having decent ventilation
  • Creating enough composting moisture
  • Adding some starters for faster composition
  • Regularly emptying your tank
Are you going to get a composting toilet? Do you have one and want to share your experiences with it? Let us know in the comments below and keep prepping!

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