The problem I see with your arrangement is that the GEC should be continuous from the grounding electrode(which is the 4" water main) to the grounding terminal bar or bus within the service equipment...250.24(A)(1)
If you were to hit the service equipment first with the GEC and then back to the bus for bonding of other available electrodes, the installation would then be inline with the requirements of 250.64(C)(3)
