Wayne Steinhauser of Hartford, South Dakota, asks:
“We sail on an impounded Missouri river lake with only one pump-out station within 100 miles. We find returning to the pump-out station is troublesome when we spend a week or more exploring and sailing. We’re thinking of installing a composting toilet. What is your opinion of these?”
Don Casey replies:
A composting toilet is one way to save a coastal or inland boat from the inconvenience of relying on inadequate pump-out facilities. However, composting toilets involve their own inconveniences.
For starters, you’ll need to keep a supply of peat moss (sphagnum) or coco peat (coir) aboard, and the peat charge inside the compost chamber must be maintained at a certain moisture level. Solids also must be stirred after every use. Although the power demand of the vent fan essential for drying is typically modest, it is continuous. Then there is the issue of what to do with urine. Despite being sterile, urine is raw sewage as soon as you capture it in a container, so you cannot legally pour it overboard. With two or more aboard, the urine containers on some composting toilets must be emptied almost daily. It seems likely most users are dumping their urine under cover of darkness.
There are other issues to consider as well. While composting toilets are almost odorless when functioning properly, proper functioning is a moving target, and odor is often the signal that some adjustment is required. Bugs, particularly moth flies, can be a problem and infestations are not uncommon. Also, heat is required. Unheated toilets work well in warm weather, but composting action is arrested by cold temperatures.
Most sailors who install composting toilets seem to eventually come to terms with all this and report they are satisfied with their systems. It may be a case of the lesser of two evils, or it may be eco-satisfaction. In the end, the only opinion that will count on your boat is yours.