Self-contained units are installed directly in the bathroom. They are available in both electric and non-electric versions. Electric units plug into a regular three pin outlet to power a fan and a thermostatically controlled heating element in the base of the unit. The unit is normally unplugged if it is not being used for 3 days or more.

Composting capacity varies with the size of the Bio-drum. Electric units normally have more capacity than non-electric units because they have extra warmth and air movement. Although advertised composting capacities can be doubled for short periods, Sun-Mar has found that wherever possible it is always better to have a good margin of safety. So, pick a unit with more capacity than you really need.

The most important advantages of self-contained units are:

• Being waterfree, they need no plumbing or water connection. This means they are quick and easy to install since the only task is to assemble the vent stack which comes with the unit.
• They are more economical than central units because there is no separate toilet.
• They are more suited to winter operations than central units, because it is often easier to keep the bathroom warm.
• Most units evaporate all liquids in seasonal operation. Since the whole waste stream is recycled, approvals are not normally required.
• Cleaning is simple. All self-contained units have a bowl liner beneath the seat, which can be removed for cleaning whenever necessary.
• The high quality, high gloss fiberglass finish is perfect for indoor installations.