Tank location?? Or drain locations??
The tanks are underneath the trailer, almost for sure. In the old days, the fresh water tank was under the seat (usually the left side) -- but since about 2008 (and maybe earlier), the tanks were suspended under the frame.
Now, if you are asking about the low point drain for the fresh tank, that should also be under the trailer. On my trailer, the drain was way underneath -- so that in order to open it, I had to crawl under, turn the handle, and get a little wet! I built a long-handled "wrench" out of wood so that I could open it. Later, I completely removed the drain, but that is another story.
Have you crawled under the trailer to look? It's not so difficult. Just don't try to sit up quickly. Please don't ask me how I know that.