Fresh water storage, a way to move it, and somewhere for the grey to go are a system, not three accessories. Jerry cans with a hand pump are simple, inexpensive, and honest about their limits. Plumbed tanks with a foot pump or a pressure pump are more convenient and introduce winterizing, sanitizing, and leak-checking as permanent chores. Grey water is the part that gets skipped: a bucket under the drain works until you forget it is there, and most public places have no legal grey disposal. Whatever you choose, water weight is significant at roughly eight and a third pounds per gallon, and it belongs low and near the axle.