Whoever built my tank put a SS tab welded onto the tank with a nut and bolt to which is connected a grounding-bonding wire. Not having that I suppose could be a safety hazard. Stuff like this I just don't think too much about, someone already did the thinking for me, lucky me. A prior owner replaced the water tank, I do know it is not the original water tank.
If you have a metal fill pipe on the tank itself, maybe you could attach the wire to that. I have a bronze pipe nipple screwed into the tank top, it would be easy to solder and or clamp on a wire to that metal nipple.