If there are not any water pipes in the detached garage you do not need bond the service switch to the water pipes. The water pipes and other interior piping in the house should be bonded to the panel installed in the house. Also you need to provide a grounding electrode at the house in addition to the electrode's installed at the detached garage. If there are any metallic paths between the garage and the house the neutral in the house panel must be insulated and a separate equipment ground wire installed with the feeder to the house panel. The grounding electrodes and interior piping at the house get connected to the equipment ground not the insulated neutral.
Curt
