I had a new home home a few weeks back that had a nail through the supply line under the tub. The only way I found it was the faucet was making a strange popping sound and it also had air in the water stream.

The hole in the line was in such a fashion that it allowed air to enter the line and just a little water would leak out around the nail. Luckily the basement was not finished and the builder had an access panel for the area under the tub. I imagine that this would have only lasted a little longer before it was a full blown leak.

__________________
Scott Patterson
Spring Hill, TN
http://www.traceinspections.com