The water system holds a fair amount of liquid after you do your disconnects. I open the two cold water drains and the one hot water drain on my rig as I'm packing up. I also remove the anode rod from the water heater to empty the 10 gallons it holds. If you leave water in the heater it causes more corrosion. So get your rig empty and you'll have fresh water next time. Else, you have old, aged, bacterial water just waiting for you.
I leave all these drains open as I drive home. Still I find water in my fresh tank and have to use levellers to rock it out. I don't want to use months old water on my next trip.
2007 391TS UFO Chassis