Assumed it was coming from the line in the wall feeding the tap, but the clean-out was strange...
Opened wall, no leak there. Enlarged hole.. found hot lines that go nowhere...
but did find the pin hole leak..
Removed leaking section...
Made hole even bigger, stuffed FG insulation in there, covered with paper & wire...
Applied mud...
When this house was built 38 years ago they plumbed in lines for an indoor or outdoor bar/sink etc. Which is why there's this bit that butts up behind the drywall that the sink drain would have been attached to... (& explains the clean-out & vent pipe in an odd area) FFS. There was also a capped off T on the cold line to the outdoor tap.
