Originally Posted by David Howe
There is a drain valve attached to a plastic pipe but when I open no water comes out. The water tank is 1/3 full.
If the plastic pipe is blue or red, it might be the plumbing low point drain. Either turn on the water pump, or connect to city water. Does pressurized water come out? If yes, that is a plumbing low point drain and not the fresh water tank drain. Also, are you sure the tank is actually 1/3 full with water in it, or just the light on erroneously?