I just came across a houseboat that had a "Raritan Head with Type 1 Purasan Waste Treatment System." I've never seen a boat for sale before with a treatment system. Could someone explain to me how they work? I've checked the internet but find just sale pitches. I also want to know if they are legal on all U.S. lakes and water ways or just certain ones. The ads I see say "U.S. Cost Guard approved", but does approved mean able to use everywhere?