The fresh water drain valve should be located in a lower compartment bin along with the fresh water pump and water filter.
There should be two "white" ABS pipes (approx. 2" diameter) coming out of the fresh water tank, one above the other.
One is located at the top of the tank (for air) and the other at the bottom edge of the tank. for draining.
There should be a "Ball Valve" (may have a red handle) installed on the lower pipe.
This is the fresh water drain valve.
If you still can not locate, contact Fleetwood in Decatur.