There are several advantages to choosing a self-contained composting toilet.  First, they are much easier to install than a remote composting toilet system.  In fact, other than installing a vent for the toilet, you will need to do little when you install the unit.  You will not need to hook the toilet up to a basement composting chamber with a self-contained composting toilet. With a self-contained composting toilet, you are getting an “all in one” unit.  The toilet and the composting bin are combined in the unit, with the composting process going on right under the seat.

Because there are few installation costs involved, and because the units are more compact and fewer parts than remote systems, self-contained composting toilets also tend to be a much cheaper option when compared to remote composting toilet systems.  (For more on the price of composting toilets, read “How Much Do Composting Toilets Cost?“)

However, this is also a disadvantage for some as well: because of their small size, self-contained composting units only have a limited capacity. If there are more than two individuals using the toilet year round, a self-contained composting toilet system is not for you.  In fact, even two individuals may overburden many models, and you need to choose your model carefully if for more than one individual.  Self contained composting toilets are probably most ideal for occasional usage in cottages or seasonal and vacation homes, or for year around usage by a single individual.

Most composting toilet manufacturers produce self-contained composting toilets (some also produce remote systems as well).  You will find that manufacturers like Sun-Mar, BioLet, and Envirolet all have several self-contained composting toilet models to choose from, each with its own unique features.  You should certainly compare the models and read different composting toilet reviews before making your final selection.

If you have more than two people who will be using a composting toilet, or if you are just interested in learning more about remote composting toilet systems, take a look at the article “Remote (Central, or Split) Composting Toilet Systems.” These systems are generally ideal for year-round usage by families or large groups.

For more articles about composting toilets, including “Composting Toilet Basics” please return to the Toilet Composting Homepage.

- a container (often called a “reactor”) where the composting process takes place

- some type of exhaust system (often fan-powered) that will help remove water vapor, carbon dioxide and any odors resulting from the composting process

- some manner in which oxygen is supplied to the composting container so that aerobic decomposition can take place

- a way in which excess liquid is drained from the composting materials
a means by which to turn the composting

- an access door to empty the finished composting

How these features are integrated vary according to manufacturers or design plans, but well constructed toilet composting systems should produce finished compost within six months to a year, and should be nearly odor-free during the composting process.

Composting toilet systems are often classified and evaluated according to the following four criteria:

1) Self-Contained Composting Toilets versus Remote (or “Centralized”) Composting Toilets

Self-contained composting toilets are units in which the toilet and the composting chamber form a single unit. Often these units will sit a bit higher than normal flush toilets, and will require a small step stool for users to easily sit on the unit.

Remote composting toilets (sometimes referred to as Centralized Composting Toilets) are systems where the toilet is connected to a composting chamber in another location, often below the toilet in a basement.

2) Batch Composting Toilet Systems versus Continual Process Composting Toilet Systems

Batch Composting Toilet Systems rely upon a single or series of composting containers in which the composting process will take place. Some composting toilet systems use a single composting container which is replaced by hand when full, while others use a carousel system where there are three to four different containers that rotate as they are filled. In the carousel system, by the time the carousel system is full, the first container will have been fully composted and ready to be used as a soil amendment.

Continual Process Composting Toilet Systems generally involve large composting chamber that are placed underneath the composting toilet, often in a basement (although there are some self contained models). Over the course of six months to a year, the composting human waste will gradually move downwards through the system and once it reaches the bottom of the chamber it is ready to be harvested and used. The process by which human waste is composted in continual processing systems varies, but most involve aerobic composition and micro-organisms and sometimes macro-organisms (usually earthworms) as well.

3) Manufactured Composting Toilets versus Site-Built (Owner-Built) Composting Toilets

For those interested in acquiring a composting toilet, there are generally two options: purchase a manufactured composting toilet (of which there are many brands) or build one on site yourself. Site built composting toilets may be considerably cheaper than many manufactured brands, but owners may find it challenging to get these units approved by local health agencies.

4) Active versus Passive Composting Systems

Active composting systems will rely on mixing, aeration and heat.  They often feature automatic mixers, thermostat controlled heaters, tumbling drums, fans and other features to promote quick and odor free waste composting.

Passive composting systems are optimized to rely on natural rather than mechanical forces. Gravity, ambient temperature and the shape of the composting chamber are all optimized to promote efficient composting.

To read more about composting toilets and composting toilet systems, please return to the main page.