I have a 90 gallon tank, and I will make sure that I put the amount of water I need in it before I leave. I just use the water hose that is connected to my house. Hope that helps.
I fill my tanks at my house prior to starting the day. I have 2 15 gallon tanks and I have a few regular customers who will let me fill up at thier houses if I run low even if I am not at thier house doing thier cars of course they get a discount in return
Just curious, what do you all pay for water? Does it depend on the amount you use? Water here in the High Sierra's doesnt cost a dime for us living here.