Composting Toilets For Off-Grid and Tiny Living

Composting toilets are great alternatives to traditional toilets in spaces that have limited or no water supply. This is because they do not need water (or only need very little) for flushing. Antibacterial gel can be used for hand cleansing if no water is available. As such, composting toilets are popular among off-grid, tiny house and green living populations.  

What is a composting toilet?

In a nutshell, composting toilets take solid waste and turn it into compost via naturally occurring bacteria. The compost produced by the bacteria is then safe to use as fertiliser in the garden.

How do composting toilets work?  

During use, human faeces falls into a composting chamber underneath the toilet pedestal/ seat. Naturally occurring bacteria in the faeces thrive on the waste, breaking it down into humus overtime. A ‘soak’ material needs to be added to the composting chamber to control moisture and help with the decomposition of faeces. It is recommended that you add the ‘soak’ after every use (as an alternative to flushing a normal toilet). Carbon material such as wood-shavings, chopped straw and coir can be used as ‘soak’ material.

The below image explains in more detail how composting toilets tend to work.

How do composting toilets work?

Do composting toilets smell?

As long as the composting toilet is properly installed, used and maintained it usually does not smell. Composting toilets tend to have tight enclosed systems that keep odours in. Ventilation systems pull fresh air in and push odours and moisture out.

However, the crucial thing that keeps composting toilets odour-free is the separation of urine from solids. Urine separation systems can be self-built. But urine-separating seat inserts are also available to buy. These divert urine down a separate drain from solids. In turn, keeping the composting chamber free from urine. However, urine-separating systems tend work best when sitting down. As such, a separate urinal may be ideal for those who prefer to pee standing up.    

Do Composting Toilets Smell?
Graphic by Amanda Goehlert

Types of composting toilets:

  • Dry composting toilet: Most composting toilets are dry. This is because most of them use none or very little (about 1 pint or less) water per ‘flush’.
  • Electric composting toilet: Modern composting toilets tend to have electrically powered ventilation fans. These produce continuous airflow to the composting chamber, keeping moisture levels consistent. Some toilets even use heating elements. These enhance the composting process by keep good bacteria alive.
  • You will need a standard wall plug, rechargeable batteries or both to power these electric components.
  • However, keep in mind that non-electric composting toilets also have some basic ventilation mechanisms. 
  • Solar composting toilet: Solar panel systems can be used to turn electric composting toilets into solar ones. The electricity produced by the solar panel can recharge batteries that power the ventilation fan.
  • You can build a more complex solar composting system by placing glass panes over septic-style drain pits. The greenhouse effect produced by the glass heats the compost, helping to keep good bacteria alive.

Bucket System Composting Toilet:

Alex Cheng shares his cheap and easy bucket composting toilet system.

Why have a composting toilet?

  • There is more flexibility in where these toilets can be placed. This is particularly useful for off grid living and mobile tiny houses as toilets can be made without needing a water supply.
  • Flushing a conventional toilet accounts for about 30% of a persons water use. Since compost toilets use less water than conventional toilets, using them is one of the simplest ways to reduce water use.
  •  Composting toilets use less energy. This is because the waste collected by them does not need to be cleaned by sewage facilities.
  • They produce excellent compost.

Things you should consider before buying a composting toilet:

  1. How many people can the toilet accommodate?
  2. What sort of maintenance will you have to do?
  3. Will you have to provide electricity for ventilation purposes?

Thanks for reading! I hope you’ve found this information on composting toilets useful. Make sure to check out the books below for some more info.

Useful Composting Toilet Books on Amazon:

If you’re in search of your very own Tiny House, then you might be interested in our post on Pre-built Tiny Houses that are for sale online right now.

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