Hippie has posted on this Forum about how he is trying to live in the outback and not using conventional methods of dumping. One post was about not using a hose. Another was about tearing out the black tank and i'm going to assume the rig is parked over a shithole.
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AFAIK, dumping grey water or sewage is not allowed anywhere there is not a facility for the catchment. That could be your own facility if you have a developed sewer system. EXceptions to dumping only grey water exist in a few places where arid climate is a problem and the effluent helps the native flora.
On state or federal parks and lands, there could be big trouble with dumping.