Is there a way to check for bonding that is not easily visible. Can I do a simple continuity test, hot to ground? If the pipe runs against something that is grounded, the meter would show ground but it is not truly bonded.
If you do a simple continuity check it will probably read that is connected to a grounded body. However, it may be just TOUCHING the water pipe. The easiest way which i am sure you already know, is connect the cold/gas/hot pipes at the water heater which can be visually verified.
Some of local AHJ require bonding of the gas pipe with at least a #6.
