Black water can go into a cess pool (
outhouse) and be buried over every few years to make an asparagus bed. The problem with putting blackwater into a reed bed, or some similar low containment area is that that practice kills millions of people every year. Even if the water never gets into the drinking water you might have a flood that could put raw sewage on your garden, that is why peasants ate porridge, they had to cook everything until it was safe to eat. Freshwater clams would also be a tempting but horrible food source, because time breeds complacency. I think that
Urine diverting toilets have been successfully coupled with BSF bins in such a way that the BSF eat the
humanure and they can then be directed to a reed bed or similar environment but keeping seepage from getting into the water is a serious concern. You want lots of good loam between the blackwater and the freshwater. Remember you don't just have to look out for your community, you also have to protect the people downstream from you as well.
