There may not be a requirment to test for continuity but it makes
sense to when messing with power showers and water that was my
point really.

It is actually safer without any continuity to the main earthing terminal.
It is just not normally possible to achieve.

The ideal situation is that all supplies are plastic and there are no
electrics. Then you don't need supplementary bonding at all, even with metal
baths and radiators.

Christian.