Composting is Nature’s Way
Every living organism consumes nutrients and creates waste. To transform waste back to nutrients and complete the cycle, nature uses the process of decomposition and evaporation. As is often the case, nature seems to be doing business in the best way possible.
That’s why Sun-Mar composting toilets are designed not only to harness these natural processes, but to optimize and accelerate them.
Toilet waste is over 90% water content. This can be evaporated and carried back to the atmosphere through the vent system. The small amount of remaining material is recycled into a useful fertilizing soil.
How Composting Toilets Work
Composting toilets break down solid waste through a biological decomposition process. After each use, a bulking agent such as wood shavings is added to encourage aerobic conditions—helping air circulate and supporting the beneficial bacteria and fungi needed for efficient composting. The combination of warmth, moisture, and airflow creates the perfect environment for these microbes to convert waste into compost material.
Little or no water is required for this process. As waste decomposes, its volume is reduced by an impressive 70 to 90 percent, leaving behind a dry, oxidized compost that is easy to manage. Proper airflow is essential; a fan system or passive vent moves air through the composting chamber, removing excess moisture and odors. Any surplus liquid is drained away—often into an absorption trench. Some systems even divert urine for later use as a diluted plant nutrient.
By carefully managing air, heat, and moisture, composting toilets turn what was once waste into a valuable resource—completing nature’s cycle efficiently and odorlessly.
Choosing the Right Bulking Agents
To keep the composting process healthy and efficient, a bulking agent is added to toilet waste—this helps maintain the right balance of moisture and air. Classic choices include wood shavings, sawdust, peat moss, and even coconut coir. These materials not only encourage aerobic decomposition by allowing air pockets to form, but they also help absorb excess moisture, ensuring that conditions stay optimal inside the system.
By thoughtfully selecting bulking agents such as these, you’re helping nature along in its recycling efforts—turning today’s waste into tomorrow’s fertile soil.
Odor Free
As well as ensuring an aerobic breakdown in the Bio-drum™, Sun-Mar ensures an odor free environment by engineering the airflow within the unit to maintain a partial vacuum at all times.
Air is being drawn in, either by a fan or, with non-electric units, by passive venting in the vent stack, over the evaporation chamber and up the vent stack. This assists in both evaporating excess liquid and ensures no smell escapes from the unit with a continuous pull of air through the venting.
Why Aerobic Breakdown Matters
The key to this odor-free performance lies in the type of bacteria supported within the system. These composting toilets are engineered to encourage aerobic bacteria—microorganisms that require oxygen to thrive. Aerobic bacteria work rapidly to break down waste, converting it efficiently and, most importantly, without producing the unpleasant odors often associated with traditional septic or holding tank systems.
In contrast, conventional systems typically foster anaerobic bacteria, which can survive without oxygen. Anaerobic breakdown is a much slower process and often generates foul-smelling gases (think of the classic “sewer gas” aroma). By promoting aerobic decomposition, composting toilets are able to process waste faster, remain odorless, and allow for a more compact and cost-effective design.
Passive vs. Assisted Ventilation
In non-electric models, this process relies on the natural “chimney effect” created by the 4-inch vent stack. Warm air rises and draws fresh air in, maintaining consistent airflow without requiring electricity. This passive system is highly effective for most installations, especially in off-grid locations or when conserving energy is a priority.
For installations where the vent stack includes bends, or where the unit is surrounded by trees or hills that could inhibit airflow, an optional low-wattage 12-volt fan can be added to boost ventilation. This is especially helpful for heavy or full-time use, as it ensures optimal air movement even in less-than-ideal conditions. The fan is energy efficient—drawing just over a watt—and can be powered by a small solar panel and marine battery for true off-grid operation.
Whether by natural convection or a gentle mechanical assist, this continuous airflow is crucial for odor-free, efficient composting performance.
Some Benefits of Sun-Mar Composting Toilets
- No septic or municipal sewage connection required
- No water required
- Uses natural processes and no chemicals
- An environmentally friendly alternative
- Pollutant free
- Converts organic matter to its essential minerals
- Completely natural process
- Odor-free aerobic process
- Results in 90%+ of the material being evaporated
- The end compost is recycled back to nature
- A safe end-product
- All Sun-Mar composting toilets have a 3 year warranty on parts. For information on Sun-Mar’s warranty, visit here.
Wherever there is a poorly working septic system, a Sun-Mar can take care of toilet waste; where there is an outhouse, we offer the luxury of an indoor facility; and where there is no toilet at all, a Sun-Mar provides the perfect solution. Sun-Mar toilets are economical, quick to install and easy to use.
But beyond convenience, there are important reasons to choose a composting toilet system that fully embraces nature’s way. Unlike traditional waste treatment systems—which often depend on slow, odor-producing anaerobic bacteria—Sun-Mar toilets are engineered to create the ideal environment for fast-acting aerobic bacteria. These beneficial microbes require oxygen to thrive, rapidly breaking down waste without producing unpleasant odors.
This efficient aerobic process allows Sun-Mar units to be smaller and more cost-effective than conventional systems. Full composting isn’t just about convenience—it’s essential for public health, safety, and environmental stewardship.
For peace of mind, it’s also important to look for independent certification. Sun-Mar is certified by NSF International, a leading public health and safety organization, under the rigorous ANSI/NSF Standard 41. This certification confirms that the system truly composts waste safely and effectively, meeting strict standards for both design and performance. To see a listing of all certified Sun-Mar products, visit here.
In short, when you choose a Sun-Mar, you’re choosing a solution that’s simple to install, easy to use, and genuinely sustainable—one that completes nature’s cycle and helps protect both your family and the environment.
