So I moved all the junk to find the top of the water tank and this is what I found.
The red hose is the filler, the smaller hose supplies to the sinks.
I filled the water tank for the first time today, no water came out of this hole, just over flowed the head faucet and the filler on the back deck.
Is this the normal set up or should I be worried I have a project ahead of me?