We have a couple of
these. I think I paid only like $8 or $9 a piece for mine though. We fill them up at home and take them with us. Usually on the 2nd day of camping, I will pour one into the fresh water tank. And then on the 3rd or 4th day (if we are out that long) I pour the other. Our fresh water tank is only 40 gallons itself. With the two additional jugs, that puts up at about 52 gallons. Just about 7 or 8 gallons shy of filling up the black and gray tank combined. You can also take the jugs somewhere there is potable water and refill. They way close to 50lbs when full though. Some use water pumps to pump water into the fresh water tank.
I also recommend getting an Oxygenics Body Spa shower head. Uses less water and gives greater pressure. Well worth the $30-35.