How many gray and black tank valves?

[Tg310]

Hi everyone,
We have a 2017 eagle ht 29.5bhds. We have two gray and two black valves on our rig. There is also a sticker on sidewall that says sanicon door location. There is no door nor did we order that option but there is a black tank valve there. Last week kitchen sink would not drain. Last valve I opened was that one and it drained. Is that normal plumbing to have that black valve?

Thanks for your help.

Tom

[RichW]

I have one valve handle for each tank, four total. Plus the Valtera terminal valve. My kitchen valve handle is under the coach just in front of the wheels.
You probably have a similar set up.

[Tg310]

Thanks for the reply
I wasnt sure why there is another black valve where the sanicon location sticker is. Seemed strange to have that sticker but not the sanicon system