It isn’t gross, so keep reading.
Our house was just a storage room and office before we moved in, without a spot to go to the bathroom, a deficiency we had to remedy before moving in. It is just a few feet above high tide level so we figured a normal latrine (with a nine-foot deep hole) would likely hit water quickly, and since we’re only going to be there for a short time, we didn’t want to make any huge permanent changes. So we did some research, talked to some Environmental Health sector volunteers, read some of a book titled The Humanure Handbook, and decided to go with a composting toilet.
Now please know that the system that we are about to describe is tailored to our needs and does not follow exactly any of the systems that Peace Corps or The Humanure Handbook recommend. However, we did keep a healthy respect for all of the sanitary and pathogen related issues involved. We carefully used the concepts taught by those respected sources to try to make a system that was going to be safe, sanitary, and yield pathogen-free results while fitting the needs of our housing site.
First, what is compost? Compost is the process of using the soil’s normal microorganisms to eat organic materials (plant based products like leaves, coffee grounds, grass, paper, sticks, vegetable waste, manures, etc.) and turn them into rich healthy soil. Normally composting is done by putting together a pile of organic matter so that the pile has the right conditions to encourage those microorganisms to be happy, multiply rapidly, and thus to eat more organic materials. When the conditions are right the microorganisms actually produce heat from all of their liveliness and this heat can kill weed seeds and pathogens in the compost pile.
Why use human waste in a compost pile? Well, any gardener or farmer can tell you that manure is good for plants and the health of the soil. If you look at the main nutrient (nitrogen, phosphorus, and sodium or NPK) values contained in various types of manure, horse and cow are good but chicken poo has very high values. Well, human manure has values comparable to a chicken in sodium and phosphorus. Nitrogen is higher in chicken poo…but that is found in human urine. So all told our waste has real potential for being a valuable source of fertilizer. Also, humanure is abundant (each adult produces roughly ½ lb. a day) and easily available. It does need to be treated to kill any pathogens that could spread illnesses before use…but cow and horse manure should also be composted to kill weed seeds that are capable of growing after a trip through the animal.
So what did we do? We purchased a 55-gallon barrel with removable lid (very similar to our old grease collection barrels from our greasecar system back in Maryland, if you ever saw those), cut a hole, attached a seat,