What is this??

[sewdarnhot]

I see a water inlet area near the back side of where the sink is located. the side where our slider is and to the left of the area where you light the water heater. What is this?
It is not our main water intake where we hook our hose to. That is on the other side.

Second...

To the right of the tank drain area past the water and plugs there are two water valves on the lower panel just under. If I turn them I get water and one seems a bit warmer - but hey - we are in Az and the temps are in the 100's so everything is warm. Question is where is this water coming from? I am using it to fill the tortoise bath and it looks and smells clean however the threading on the end where you might say could connect a hose to is a lot smaller than a hose. I would love to be able to get a hose connected to the line to have outside water. Can anyone help.?
I need a darn schematic to tell me what everything is. Kinda learning as I go.

[Pipeman]

Just off the top of my head, that inlet could be the flush for your black tank. The other valves could be your low point drains. I have used mine to fill a dog's water dish, etc.

[bikendan]

pics are always better than descriptions.