How to tell if water pipes are grounded?
My cold water piping is bonded to the panel at the cold supply of the clothes washer. The hot piping is presumably electrically connected to the cold through the brass mixing valves of the shower and tub. There is negligible resistance between the cold and hot pipes at the washer supply valves.

Following Tyson's link I see my kitchen and lavatory faucets are not bonded because they are connected with non-conducting flexible supply lines; an ohmmeter test confirms this. I tested this by plugging an extension cord into an outlet and measuring the resistance between the ground of the cord and the point under test.