could electricity "leak" in a home through badly ground pipes copper or other metal (?)
hypothetical~ if my copper pipes were not grounded properly causing corrosion to the water heater would that in any way use more electricity increasing the monthly kilowatt usage?
No, electricty would not leak in the way that you described (i.e. on a continuous basis).
If it did you would be in danger of electrocution EVERY time you touched a faucet or metal sink. I was testing a customer's system one time with a "TicTracer" which responded to electrical currents. When I went past their refrigerator, it "lit up". The reefer housing was "live" and the only thing that prevented them from shocks was that there was no plumbing nearby that they could touch at the same time they were at the refrigerator.