Join Date: Apr 2006
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The US EPA has a PDF file online about composting toilets. No pun intended, but the "bottom line" is that most of what are being sold as composting toilets for boats? Aren't.
The EPA recognizes two kinds of composting toilets. One, where the waste gradually fills a bin so that what you are removing is typically a year old, as it progresses down from the toilet. After a year in the proper conditions, it has composted and is no longer hazardous sanitary waste.
The other, requiring AT LEAST TWO BINS or composting units. You use one, the either swap it out or move ot the other, and ALLOW THE FIRST BIN TO COMPOST for at least a full month. Longer depending on conditions.
So...composting toilet for boats? Unless you have two of them, or two bins and space to swap them out, it is nothing more than a cedar bucket with aspirations to be something more. And what comes out of it, is still "sanitary waste" that requires the appropriate permit and special handling to be disposed of, or buried, ashore.
I know, waste is waste and a "dry head" may still be more convenient than a holding tank full of wet waste. But as far as I can see--the things being sold as composting toilets, for single installation on boats, just aren't going to generate any kind of sterile safe compost.
Of course, they're way easier to find than plain old cedar buckets. :-)