Its been mentioned that grey water is sewage, period. Well, not really. In some agencies definitions, it may well be, and its not a bad thing in their situation. They dont have any way to easily distinguish between grey and black water, and people being people, many would claim any release was grey, but its not as clear cut of a distinction in other ways. Disposal of greywater has different requirements in different places, besides federally regulated recreation lands and its an evolving situation.
When I first had a cabin in the frozen wastelands in the northern rockies, it was fine to discharge grey water on the ground on private property in the 1990s, so i did. I had an outhouse, so no actual septic system. I checked with the county and there was no restriction at that time and place if it wasnt near waterways or a well. Some years later the state established greywater use and disposal regulatons, which are very different than black water rules. The result of my grey water discharge was the grass grew nicely in that area. It was sandy, gravelly soil with an incline, it didnt pool up, just ran off and dispersed into the ground and evaporated.
Anyways, this is just a clarifying note to some reading this thread that may be horrified that some cretins may be discharging or disposing of "sewage" in a manner they think may be dangerous, when its not, when properly done. On BLM lands, yes, thats the rules. Live by them. In the rest of the world, no, people arent doing the same as dumping black water out into the world and creating disease potential that black water or human sewage would.
Some info on greywater issues
https://greywateraction.org/greywater-codes-and-policy/