Is grey water treated enough to ensure we don’t get e-coli from its use?
edit: also, greywater in this case is usually captured from rainfall, not recycled from sewage, like you might be thinking.
Contaminated crops usually uptake the pathogens from their water intake rather than from "dirty handling" and given it's within the produce itself, you cannot "wash it off". Cooking solves the issue, of course, but not all produce gets cooked.
Your going to have a bad time when you find out what most organic fertilizer comes from.