Water fill line leaking how do I access it?

I am going to look for my water pump today I think access to it is under the bed if I have easy access to it I will buy one of those valves for winterizing thanks for pointing that out I have owned many RV's over the years and never knew they had that product. This is why I like this site I learn new cool stuff all the time.

I learned about the battery watering kit on here and put that on man does that save time this product also looks like another big time saver.