Found leak, hot water line?? and hot water tank question

[pdxpfeifer]

Hi Everyone -
I turned on water today to try and spot that that was leaking, my picture attached is kind of hard to see. So in front is a 3 way line running out of the wall from the bathroom. The one that is shiny and new looking is the one we paid to have replaced.

The one behind the new one - both are T shaped, one coming out of wall, one going forward (to hot water heater) and the top of the T goes up to the sink.

The one in the back is leaking and the connection is perfectly round?!? I do not seem to be able to put a wrench on it to turn it?? Looks rusted and possibly original?

Is this the hot water line and how do I get it off to replace it? The connection is is right up against the wall,even if I could cut it off - I would not be able to run a new connection nipple onto it.

I will also included photos of the hot water heater in reply for the inlets and outlets are super rusted. I have not even had the chance to see if I can get the hot water heater to work in between all the other challenges LOL

[pdxpfeifer]

Here are the hot water heater inlets that are all rusted, the leaking water line in question goes into the small bottom inlet of the hot water heater

[pdxpfeifer]

this is the wall inside the kitchen inside the cupboard kitchen area the wall against the bathroom wall, delaminating and coming apart - a leak???

How can I tell if it's a current leak or old one? Is there a way to tell if it is coming from water