The fresh water drain on my 2007 is the same generic type used on an insulated water jug. Assuming you have the same, you should be able to pop off the turning handle portion from the rest, and snap the new one in. I would leave the rest alone unless it leaks or the parts are not compatible.
If the valve is hard to turn or is leaky, on my favorite water jug I simply clean it well and then smear a light film of Vaseline that keeps it turning easy and seal well for about 3 years which then I'll repeat.