Compost Toilets

Compost Toilets

How Compost Toilets Work


Compost toilets convert human waste into compost using little or no water.  The toilet uses aerobic decomposition, essentially the same process that converts wildlife droppings into nutrients for the forest, to convert waste into fertilizer.  City waste treatment utilities use a similar process. If you have ever composted kitchen scraps, then you already know how compost toilets work.  Aerobic bacteria break the waste down using air and heat.

The material being composted needs to be stirred from time to time to continue introducing air for the bacteria to do their work.  Adding materials such as sawdust or popcorn also help the bacteria.  Over time, the decomposition process completes and the result is a nutrient filled material known as humus.

Compost toilets come in two varieties – self-contained and central.   Self-contained compost toilets are typically smaller and are the types that are usually used in seasonal homes.  They are combination toilet and composter units.  The composter in a central system is a large container outside the home. Self-contained units are best for light uses, whereas central units have a larger capacity for use year round in a typical home.  As you might expect, central compost toilets are more expensive than self-contained models.

The toilet part of a compost toilet looks very similar to a standard flush toilet.  It has a bowl and a lever that you use to flush. The difference is that the flush is waterless and the waste goes to the composting unit as opposed to the sewer or your septic system.  Some compost toilets use paper bowl liners to carry solids to the composting unit.

The first job of a compost toilet is to separate liquids from solids.  Liquids are usually collected in a smaller tank that needs to be emptied when full.  In other systems, the liquids may be disposed of using the plumbing already in your home.  Note that unlike a flush toilet, the only liquid that needs to be disposed of is the liquid that comes from human waste.

Once in the composter, the solids are stirred to introduce air so that aerobic decomposition can take place.  Some compost toilets have heaters that keep the compost at the proper temperature.  Some allow the introduction of materials such as earth worms to make the decomposition process more efficient.  When the composter is full, it is emptied, and when the decomposition process is complete, the resulting humus can be used as garden compost, as it is will be free of harmful bacteria.

You may think that compost toilets would stink, but with the aid of a small fan that exhausts odors to the outdoors, and except for a slight mustiness, compost toilets do not smell at all.

Compost Toilets

 Please continue reading my Composting Toilet – 2 product review and visit my Compost Toilet Store. Also see my other review posts for this green living product: 

Fifteen best features of composting toilets.

What makes a composting toilet green?

Composting toilet FAQs.

Composting toilet tips and tricks.

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