I would like to know if it is actual code or if only certain areas require grounding plumbing and gas lines within the house.

And if so , why?

My cousin is building a house where there are no inspectors nor permits required.

His water and gas line feeds are plastic/PVC. Once they inter the house the water line is copper and (not sure about gas line). Is he required to bond to these metallic lines? It seems kinda dangerous to me, being that if the main neutral ever gave up. It's load has to go somewhere doesn't it? What if your taking a shower and it decides to use you as its path? Singing in the shower is one thing, but dancing is not preferred. Comments please.

Thanks