do you keep water in holding tank between trips?

I always leave my water tank 1/2 full , drain it when I get home and refil with city water . My grey and black tanks get flushed when I get home ( have my own cleanout to the sewer) And then I add about 5 gallons to each after they have been flushed , So on my next trip it keeps things loose in the holding tanks , and I have fresh water in my supply tank if necessary.