I was checking over the 'piping' on my 2018 Sunseeker MBS 2400R, to winterize and sanitize in the Spring. Drains are fairly easy to identify, but this second inlet to the top of the fresh water tank baffles me. I assume the corrugated hose is the fresh water fill from outside. But, what is the white reinforced 1/2" line into the tank? Curious minds want to know.