Seesh, we’re all too removed from a lot of this stuff. I’ll wager there is no ‘raw sewage’, or even anything close coming from these outhouses going on to any fields that raise foods directly consumed by humans.
Amish are old fashioned, not stupid.
Check out any large dairy farm or hog farm. The excrement (i.e. raw sewage) is collected, stored, loaded into tanks or wagons pulled by a tractor, and sprayed on the fields. Any excess is simply sprayed on the farm next door, you know, the one that doesn't have cows or hogs, but grows tomatoes or cabbage, and that farmer says, "Thank you".
Are we heading for an Upton Sinclair moment?? Ban manure and our food production will gradually decrease to the point where we won't be able to feed ourselves much less the rest of the world.