Draining hot tub after boondocking? Grey water..

Sounds like a great idea! If you are going thru the trouble to filter it coming in then whay not filter it back out? Heating would be an issue. Maybe hookup a Girard tankless as a heater while filling the tub and then circulating it through. I can only imagine you will get more grief just filling something like that should a leo cruise through... so just keep it stocked with attractive people...