Something is very wrong. Your electrical panel should be grounded to a ground rod somewhere. Depending on a cold water pipe for ground is not safe. I assume you have an older home. Current does flow to ground. Without ground you can not have a complete circuit.
Sparking Ground Wire
"My electrical panel in my house is grounded to my cold water inlet. I replaced the worn clamp to the pipe and noticed a small spark when I touch the ground wire to the pipe. What could be causing this. My understanding is that the ground should be dead and should have no current. Any suggestions?"