I find holding up a heavy water jug while it slowly pours down the tube into the fresh water tank to be a bit taxing given the weight of water. Furthermore, with a 5 gallon jug and a fresh water tank holding approximately 30 gallons it has to be repeated 5 times if the intent is to fill the tank. So in those rare cases where I do not have city water, an empty fresh water tank, and water is available from a spigot in the area, I have a couple of collapsible 5 gallon water jugs. I fill them up on the tailgate of my truck, back up beside the trailer and use a Mega Siphon / Safety Siphon to accomplish the transfer with little effort. These self priming siphons are available from Amazon and other sources. Put the business end into the fill tube, and pump the siphon end up snd down in the jug until flow starts.
What a long strange trip it’s been!