1990 six pac camper sc100

oh wow ok....I have the camper off the truck and on blocks right now. I didn't even think to look on the tank!! Ill jack it up when I get home today and see if I see anything. I was only looking at the back where the drain valves are located. The tank still had water in it from the previous owner he just got back from a trip to Vermont. Luckily he dumped the black and gray tanks but left the fresh water tank with some water in it. It wouldn't be a big deal but I don't know when I am going to be able to camp in it, so I didn't want that water just sitting. I have to get my truck rigged up first with some tie downs.