Finding where the leak in the line is difficult but finding out if you have one is a little easier. To find out if you have one, you can shut off the main shut off in the house, where the water comes in. Then go out to your water meter outside and see if it is still running...there is a good chance you have a leak in the main run feeding the house. Usually, unless you know where it is and can do a spot repair, we run a whole new line because if it has started to fail in some spots, chances are it may start to fail in another.
Pan is installed sometimes to catch little leaks and send them down a drain or if there is no drain, it is meant to catch leaks so you have a chance to see them before it causes too much damage. Hope that makes sense.
I HAVE A LEAK FROM UNDER MY DISHWASHER BUT IT DOES NOT LEAK WHEN THE DISHWASHER RUNS BUT INSTEAD IT LEAKS FROM THE OTHER SIDE OF THE WALL WHEN I TURN THE FAUCET ON OUTSIDE, DOES ANYBODY KNOWS THE REASON FOR THIS LEAK??
If I am understanding you correctly, the wall the dishwasher is on is an outside wall and when you turn the faucet on outside the water leaks inside . . . if that is the case, your hose bib sounds like it is leaking behind the wall and the water is just leaking by the dishwasher because that is the easiest place for the water to go. You may want a plumber to come take a look.
