A composting toilet is a toilet which converts human waste into compost, a nutrient rich organic soil which can be used in agriculture and horticulture. There are numerous advantages to using a composting toilet, ranging from the fact that these toilets are extremely water efficient to a source of free fertilizer for the garden. Several companies manufacture composting toilets commercially, and it is also possible to build one relatively cheaply.
The basic goal of a composting toilet is to break human waste down, rather than to flush it into a sewer system and treat it, using huge amounts of water and chemicals. This break down is accomplished with the help of aerobic bacteria, which are encouraged to thrive, reducing the volume of the waste to around 10% of its original size. In the process, these bacteria remove harmful pathogens from the waste, converting it into a soil which is rich with nutrients discarded by the body.
Many composting toilets use no water at all, while others utilize a very small amount. Waste is deposited into a central drum which is periodically rotated to ensure good air circulation; other composting toilets are aerated by hand with rakes, or sometimes with electrical devices. Depending on the climate and the type of composting toilet, it can take between three months and three years for the waste to break down all the way.
Proponents of composting toilets argue that they are good for the environment, and the resulting “humanure” can be used to fertilize all sorts of crops. Some people recommend that the compost be used only on flowers and as a mulch for things like fruit trees, to avoid the risk of potentially contaminating plants which are eaten directly like leaf lettuce or other produce. Humanure can also be pasteurized to remove any potential pathogens, and some composting toilets include a feature which turns urine into a rich liquid fertilizer. In some nations, humanure is even used in industrial agriculture.
Composting toilets can be used in all sorts of applications. Some regions use them to replace portable toilets, for example, and stock convenience toilets with composting toilets rather than water-based models to reduce maintenance costs and to be more environmentally friendly. They can also be used for recreational vehicles and homes which are built off the grid. People on the grid can certainly use composting toilets as well, and numerous commercial models conform with building and safety codes for people who want to build “by the book.”
One concern which is often raised about composting toilets is the issue of odor. A well maintained toilet should not actually produce any undesirable scents, but the contents of a composting toilet can also be amended with materials like sawdust and sand to absorb odors if they become a problem.