Purpose of this switch?

[Lawrence Tarnoff]

In my never-ending quest to better understand our coach's systems, I hope one of you folks will enlighten me to the function of the toggle switch located below the tv/phone ports on the water distribution panel.  I thought it might activate a black tank flush, so I pressed it when I had water running into the flush input.  Immediately got a dump of fresh water forward of that bay.

Thanks!

[David T. Richelderfer]

That sounds like the drain valve switch for the fresh water tank.  I think my switch says "Fresh Water Drain."

I do not have a switch for flushing the black tank.  I hook up the hose between the city water faucet and the "Black Tank Flush" hose fitting on the water bay panel, then turn the water on at the faucet.

[Jerry Emert]

Lawrence, mine is also a fresh water dump switch.  First time I experimented with mine it stuck open and I didn't realize it.  Couldn't fill tank for weeks until a friend found it and pushed it closed.
Jerry