Our Patented Design

Sun-Mar’s Patented Three-Chamber System

A composting toilet must perform three completely separate processes:

  • Compost the waste and toilet paper quickly and without odor
  • Ensure that the finished compost is safe and easy to handle
  • And separate, and/or evaporate the liquid contents

Sun-Mar toilets fulfill these requirements with our patented Three-Chamber design*. These toilets consist of a Bio-drum™, a Finishing Drawer and an Evaporation Chamber.

Sun-Mar’s Unique Bio-drum™

The ideal way to compost waste would offer operational simplicity, and an environment where there is warmth, moisture, organic material and oxygen. Sun-Mar creates this ideal environment in the patented Bio-drum™.

The unique Sun-Mar Bio-drum™ ensures aerobic microbes flourish and work much more quickly to break down waste and convert it back to earth.



At above 60% moisture content, liquid starts to drive out the oxygen in the compost, and the compost becomes increasingly anaerobic, similar to a septic system. Sun-Mar’s unique Bio-drum™ optimizes composting speeds by automatically draining any excess liquid through a screen at the bottom of the drum directly into the evaporation chamber.

Moisture control, the other basic requirement for good composting, is one of the outstanding benefits offered only by Sun-Mar’s Bio-drum™.

When moisture content drops below 40%, composting slows and eventually stops completely.

Waste and bulking material mixture enter through the waste inlet port at the top of the drum. To mix and aerate, rotate the drum periodically, simply by turning the handle on the front of self-contained units or on the side of central units. During rotation, the inlet door closes automatically keeping the compost in the drum.

Sun-Mar’s unique Bio-drum™ design is the easiest and best possible way to thoroughly and completely mix and oxygenate the whole compost.

Rotate the drum, and the entire compost pile is tumbled and infused with oxygen. Oxygen is one key ingredient which allows aerobic bacteria to break down waste quickly and without odor.