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The Sun Frost CS composting toilet composts all of a households organic waste; both human manure and food scraps.

by Larry Schlussler PhD on February 15th, 2013

We have recently developed a new low cost composting toilet which is capable of composting all of a homes organic “waste” (really organic resources).

The Sun Frost CS composter system incorporates a sleek interior toilet and two 55 gallon batch composters outside to finish the composting process. Food scraps can be added to these composters. This increases biodiversity and actually makes the composting process more effective.

The Sun Frost CS composting system does not require a drain field or have large electrical requirements to evaporate liquids. The only electrical requirement is about 2 watts for a ventilation fan. The fan can be provided in DC for solar applications or AC for grid tied installations. Odor in the bathroom is controlled by two methods, covering the toilets contents with saw dust or peat moss and a fan powered ventilation system. Even without a ventilation system, covering the content of the toilet with sawdust has proven itself effective. For many years, a similar home built toilet system outlined in the “Humanure Handbook” effectively utilized this strategy. With the incorporated ventilation system the Sun Frost CS is even more odor free than a conventional toilet, since the odors produced while using it are expelled directly outside.

If you only use the CS toilet it will take about 1 week to fill the 5 gallon interior storage container. If only solid waste is added the toilet will take more than 2 months to fill the interior container.

With this batch composting system one exterior drum is filled while the composting process is completed in the second drum. The 55 gallon composter only requires the addition of a dry material, such as wood savings. Wood shavings are readily available in feed and pet stores. Effective composting requires aeration (mixing), proper moisture content and warmth. Mixing in the 55 gallon drum is easily carried out with the stainless steel “cork screw” type mixer provided with the kit. The exterior drums are insulated to keep the compost warm, which speeds the composting. During winter months under very cold conditions the contents of the drums could freeze. Human manure and compost can still be added to the drum, composting will continue during warmer weather. A scoop, provided with the kit, makes emptying the drums a simple matter. When emptied the contents of the drum smell and look like healthy top soil.


We have had the contents of these drum composters tested for fecal coli form and have found the level to be extremely low. The secret of making safer pathogen free compost is keeping the process aerobic, which is achieved by mixing and adding sufficient dry material. The open top drums for the 55 gallon composter can be obtained locally. This significantly reduces shipping costs. Included with the Sun Frost CS are insulation and insulated lids .


Other composting toilets with a small foot print do not provide outside composters to finish the composting process; it would be up to the home owner to provide a sheltered composter to complete the composting process. The Sun Frost CS is easily assembled and provides a convenient way to compost all of a households organic waste.

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