My water sediment filters turn red/brown after only a few months so perhaps the water is mildly conductive.
Lucky you. I have to change my sediment filter element every 3 weeks. (It's a standard 2.5" dia. x 9.75" long string wound cartridge, 10 micron.) I haven't measured the conductivity of the water, but about a year and a half ago the jet in the pump plugged up with some larger metallic chunks.
There is copper, some steel, and some plastic pipe in my house. Besides a grounding rod, the service is also bonded to the cold water pipe at the water heater. However, about 15 feet away, the cold water pipe transitions to a length of plastic. Somewhere beyond the plastic is more copper pipe, which is not bonded. Somewhere there's a chunk of steel in the mix. Neither is the copper hot water pipe bonded. Where the pipe enters the earth, it's plastic.
Really, all the sections of metal pipe should be bonded, not to provide a ground path for the electrical system, but to equalize the voltage potential on those sections. This can be especially important with gas piping, to reduce the chances of a static electric discharge creating a spark in the presence of a gas/oxygen mix. (At least, I think that's the theory behind bonding all that stuff.)