Composting Toilets – Frequently Asked Questions

What components make up a Sun-Mar Composting Toilet?

Sun-Mar has a Three Chamber System

  1. Compost the waste and toilet paper quickly and without odor
  2. Evaporate the liquid
  3. Ensure that the finished compost is safe and easy to handle

Sun-Mar Composting Toilet ComponentsLEGEND

  1. Fan
  2. Screen
  3. Emergency Drain
  4. Thermostat
  5. Air Intake
  6. Heating Element
  7. Gear
  8. Bowl Liner
  9. Drum Handle
  10. Drum Door
  11. Drum Bearing
  12. Drum Lock
  13. Composting Drum
  14. Finishing Drawer
  15. Heater Base
We have no electricity. Is there a non electric unit and does it work as well?
There are several non electric units available. They are just as efficient as the electric units in the composting of the waste. Non electric units do not have a fan or a warming heater to aid in the evaporation of the liquids so it is important to install the overflow drain in these units. The composting action and drum are identical in electric vs non-electric units.
We do not have a pressurized water system. Can we make a flush toilet system work for us?
The flush toilet style requires about 4 psi of water pressure to operate. This can be achieved by most gravity water systems. We also have 12 volt water pumps to supply ample water pressure from rivers, lakes or storage tanks. There are also air flush units that have a toilet style top and a centrex composter unit located below which require no running water.
What happens to the waste?
The waste that we think of as solid is actually 90% liquid. The bacteria in the drum break up the waste and produce water, carbon dioxide and heat.
Why is there no odor?
The bacteria are operating in perfect conditions in the bio-drum. They have oxygen and moisture and the waste is mechanically broken down by the tumbling action of the drum (which also brings oxygen into the compost) With oxygen the bacteria produce very little methane (odor). Sun-mar composting toilets are designed to maintain a partial vacuum in the units at all times. Fresh air is always drawn into the units and vented up the vent stack to the roof (the vent stack and roof flashing is included with every unit). This ensures that the units are odor free.
How often do we have to 'dump it'?
Most of the waste is liquefied and evaporated, but eventually the compost accumulates in the drum. When the drum is 3/4 full some of the compost is dumped into the secondary composting tray. The compost remains in this tray until the primary drum is 3/4 full again and needs to be dumped. The secondary composting tray has now had at least 3 weeks for the bacteria to finish their work and the compost is ready for your flower beds. Weekend users may only need to ‘dump’ their units once a year. Fulltime users may need to dump their units every 3 weeks.
What do we have to add to the composter?
The Sun-Mar composters require the addition of a “compost sure” peat-moss based mix as well as water and human waste to work. Compost sure has wood shavings or hemp stocks to greatly improve the composting action of the units. Compost sure is added at a rate of one cup full per person per day of use.