In my read of the article posted by e57, the water heater is a natural place for bonding. In this area interior copper is the usual plumbing, but the well is in PVC. As stated by others, the issue is bonding, not grounding. The water heater typically has dielectric unions and it's possible that all the faucets will be plastic. Another good place for a jumper IMO is the softner which usually has a plastic bypass. This bonds all the interior plumbing unless someone patches in pvc.
Dave
