We have exactly the same camper. Even the same year. The drain for the fresh water tank is on the front left corner under the bed. The drains for the water lines are on the left at the bottom of the kitchen cabinet. They are rings that you pull up to release the water. The water pump is behind the fresh water tank on the left and very hard to see. There is a clear vinyl hose coming out of the pump that you can put into your bottle of antifreeze. I put a mirror at the far back behind everything and it makes it a little easier to see what you're doing. I also added a door into the area under the bed, I have a post here that will show you the actual valve to the water tank. https://wackypup.blogspot.com/2016/0...our-views.html
You might enjoy taking a look around my blog about our camper I have a lot of mods to increase your storage and make it more comfortable. We love our Fun Finder X 189fbr!