From some posts here, apparently many homes continue to be grounded via the water line.
This hasn't been acceptable ( up to code ) in decades. I mean, there's no requirement to fix this, generally, but you may no longer rely on copper pipes for new construction and upgrades. You MUST use grounding rods (sometimes more than 2, depends on soil conditions) for the electrical ground and they must connect to the neutral only at the service entrance. Any sub panels must maintain the ground/neutral separation.
There are some requirements to ground copper pipes, which I forget why, but you don't use them as electrical safety grounds. Not only are the connections iffy, but with modern water pipes using mostly plastic it is quite easy to find an older home which has plastic in the middle.