Several times in the past I have seen RVers using a macerator pump and some sort of holding/transfer bag to dump their holding tanks. They had the bag in the bed of their truck and used the pump to fill it. They took it to the dump station to empty it and then just folded it up and put it into a storage compartment. I have also seen people use these bags fresh water refills (clearly not one bag for both sewage and fresh). Anyway it seems like a nice way service a RV when parked at a dry site for an extended time. I wasn't interested enough back then to ask where they got the bag but now I am. Anyone ever seen these bags? Are they a good idea? Do you know where to get them?