I don't drain my fresh water tank but once a year.......in the fall when I winterize.
If I don't use much water from the tank during a dry camping trip, I will pump the excess into the black and gray tanks so those will dump better. I will watch my fresh water tank gauge, and when the 1/3 light goes out, I stop the pumping. I like to keep some water in the tank for toilet flushing and hand washing while on the road.
Chap , DW Joy, and Fur Baby Sango
2006 Ford F150 Super Cab 4x4
2008 Surveyor 263