I have a client who just contacted me regarding a hole in a water pipe that broke 10 months after the installation, which she says we caused installing 3/4" hardwood flooring. Do you think it is possible a nail can hit a water pipe? And if so am I liable? Why would a water pipe be so close to the flooring? There was a plywood floor that we installed on. I know the nailer shoots nail at about a 45 degree angle. It is possible it was near the start or end of the flooring where you need to use a finish nailer

There are plumbing codes that dictate the location of water pipes. If the pipe is NOT installed per code, you may not be liable. Water pipes also run in walls. What about the carpenter or floorguy who is nailing up basedboards? If a waterline is too close to one side or other of a wall stud, the installer could puncture the line as well. Plumbing lines must be installed in locations where they will not likely be penetrated by a nail or screw. Before I would accept liability, I would want to see exactly where the water line is and find out if it's location meets local plumbing codes.

So ya nailed a pipe.
It happens, then leaks months later.

Strange that you nailed to 3/4" Plywood and still had enough length to nail the pipe and make it leak. Was this pipe in the floor or the wall, or Near a Wall?