I have a 2008 Discovery 40X. I can't find where the valve is located so that I can drain the stagnant water out of the fresh water tank.The factory site hasn't been much help other then to send me a drawing showing me where the valve should be. Nope it's not there
My discharge valve is in the same compartment as my water filtr, it is a plastic valve with a red handle. it is also connected to the fresh water overflow line. Hope this helps
You might look for a "low point drain" valve. Our Southwind has both hot and cold water low drain valves located near where the water pump is.
Hope this helps.