If the light is in the water (below the water line) touching it by foot would not be any different than not touching it. The bath water is a conductor and the whole tub would have the same potential. I also assume you meant to say 15 kV instead of 15kVA.
I did have a case where the drain in a residential shower would show 120 volts between it and the shower handle - only when the water was running thru the drain. After talking to the plumber who had worked on the drain several times, i found out that it clogged frequently and he would run an auger thru it. (The shower sat on the ground floor of a slab home.) I assumed the pipe came apart, the auger nicked the wires and would conduct when water flowed.
I capped off the line at the panel and rerouted the power from a plug in an adjacent room.
The ground does conduct electricity and it goes from a point of higher potential to a point of lower potential. Adding ground rods would be a waste of money and time. Sounds like they have plenty of ground connections...
