I live in a floodway - that's the area right next to a river that WILL flood if the river runs over its banks. (A floodplain 'might' flood, being further back from the banks.)
Anyway, it's one reason I built a tumbler-type composter for my toilet. I can't depend on year-round safety re flooding, even if it's only once every 10 years, & the local health department would have a conniption if the river flooded & shoved partly-composted material downstream. Can't say I have any argument with that..
Being only 1 person, I have had a problem getting the tumbler to achieve the temps needed for proper composting so I (a)put a layer of chopped paper insulation over every use of the toilet; (b)spray every use with enzyme spray of the type used to de-stink kennels & your favorite rug; & (c)put a heater under the tumbler to insure the contents will get hot enough, since 1 person doesn't generate enough food scraps & humanure to get the unit up to temp & keep it there, easily.
I also pour in the liquid from plain yogurt, which I eat a lot of, to innoculate the compostables with lactobacillus bacteria, which also promotes faster breakdown.
The unit is inside - I'm NOT going out to use the john in the middle of the night & even less so when it's below 0 F out there. Besides, with the oil boom here, we now have a much larger problem with homeless people wandering thru everywhere.. think about that in the outdoor john at dark o'clock.. Pass!
I pass this information along in case anyone else has come up on these problems. I buy a bale of chopped paper (ie, 'blow-in' insulation) for about $8 every few months. It's not treated with anything, is advertised proudly as 'green', & does a whizbang job of soaking up fluids. The enzymes make sure there's no odor & that breakdown occurs.