Wondering if anyone can provide some insight. I discovered that there was a water leak behind one of my walls and when I cut out some drywall to inspect the situation I saw that there was a water leak at the union of the copper pipe with the plastic tubing (I believe it's pex). The copper and plastic tubing seem to be joined with what seems like a putty like substance. I've never seen copper pipe joined like this. It looks rather ghetto and not up to code. Is this normal? What is this joining compound and can I use it to fix the leak at the joint?