A composting commode uses little or no water, and in this type of commode, bacteria is used to break down the waste that is placed in the commode and make it into a compost, or fertilizer, that you can then spread on a garden or in another area to help plants grow. Composting commodes are often used in areas where water is precious and where indoor plumbing is not available or not desirable.
Shredding commodes are used in areas where no plumbing is underneath the toilet or is unavailable to remove the waste. These commodes are often installed in basements as an additional toilet. They shred the solid waste and mix it with the liquid waste and then pump the slurry out to the nearest sewer line via a sump pump set-up. These toilets can literally be placed anywhere, without having to worry about drain lines being run through concrete or other surfaces. You can also use shredding commodes in RVs, which you empty at appropriate pumping stations, usually called "dump sites."
A number of different types of water-saving commodes are manufactured. Some rely on low-flush volumes, such as 1.6 gallons per flush toilets, while others rely on using only a splash of water that is dumped from a bucket in the toilet's tank when the flush lever is depressed. These commodes are effective because they rarely if ever leak due to their design.
Bidets and water toilets are commodes that have the added function of using water to wash off the areas of the person who has just used the commode, so you don't need toilet paper. In addition, an additional level of cleanliness is in place, since your body is squirted clean with water immediately before leaving the commode.