In contrast to a classic outhouse, the composting toilet has a decisive advantage: the excretions collected in it (i.e. faeces and urine) are processed into nutrient-rich humus and – strange as it may sound – returned to the natural nutrient cycle. In other words, our legacies can be used as plant fertilizer. This makes a composting toilet an economically and ecologically sensible alternative to a chemical toilet. This article summarizes how this works in practice and what you need to consider before using it.

Unlike a chemical toilet, human waste is collected in a container filled with bark mulch or eco-chips. The litter primarily serves to bind odors by binding liquids. But how exactly does composting work – and how is the organic toilet cleaned afterwards? We explain it to you.

The principle of a composting toilet is easy to explain: First, the excretions are collected in the container underneath or in a compostable garbage bag and covered with litter – then disposed of in the garden compost (including toilet paper). Pre-composting begins during storage in the bio-toilet, but it still takes at least two years before you can reuse the finished compost in the kitchen garden. You can also add organic waste from the garden to the compost heap to speed up the process. Water, on the other hand, is more of a hindrance, so the collection point should be protected from rain. Be it through a cover (make sure there is sufficient oxygen exchange) or a shelter.

Another question deals with cleaning a composting toilet. In contrast to a conventional toilet, there is no running water, so neither a classic toilet brush nor an aggressive cleaning agent is recommended for cleaning. In fact, you can only clean the surface of the seat, for example with a clean cloth and some washing-up liquid – or you can use a disinfectant spray to combat and eliminate possible bacteria on the toilet seat.

Tip: By the way, every mobile camping toilet can be converted into a composting toilet.

Pathogens that are harmful to health can be found in human excretions such as faeces and urine. For this reason – according to the World Health Organization (WHO) – it is essential that you let the natural fertilizer that you “grow” on your compost rest for at least 24 months – only then can it become hygienically pure. However, by pasteurizing (i.e. heating to at least 70 degrees, for example in an oven) you can reduce the long-lasting process to two hours. From a legal point of view, it is only important for you to know that the use of a composting toilet in your (small) garden at home does not pose any problems. However, you may not use compost made from human excrement for commercial or agricultural yards. That is forbidden.

If you are still wondering how human excrement can be turned into natural fertilizer: With the help of numerous microorganisms such as worms, bacteria, algae and fungi, the residues are decomposed and processed into fine compost.

Important to know: Alternatively, the residues from the composting toilet can also be disposed of in the organic waste bin if you are not interested in making hummus for the garden.

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