I use a collapsable 5 gallon water container from Walmart, and hose clamped a length of water hose with the fitting on one end to fit the outlet of my camper. Works well, no major issues with the campgrounds, plus it comes in handy when you need to douse a burned out campfire before breaking camp.
Good luck
We carry a small 3gal bucket (from homedepot in paint department) that we use to catch the water and it stores under the couch fine. It serves double duty (haha) as an emergency bathroom if needed somewhere (assuming no water is in it): Put a trash can liner in, spring some kitty litter in, go, more kitty litter and knot the bag off.