wrote in message
oups.com...
"He had put the ferrule in backwards in a compression fitting
in the bathroom."

Not that I'm an expert on ferrules, but the ones I recall were
symetrical. Aren't they?

This is a 3/8 inch plastic supply tube for a faucet. The ferrule is not
symmetrical. Shallow taper against the nut and sharper angle taper against
the valve. Flip it over and it'll leak.

Bob