A woman died from this while stepping out of the shower. The husband was suspected of premeditated murder. Can't remember the details of this case. It might have been in EC&M magazine.
It might be a Phantom Voltage and so it may not be deadly but I would pursue this.
If you run any incand. bulb from the recept cover plate screw to the water and it lights, it is deadly.
How come your GFCI didn't trip?
BTW, from a GFCI protected outlet I just ran a wire from the short slot to a steady stream of water from the bathroom sink.
No trip, but the sink faucets and drain for this basin are connected with non-conductive piping. I guess this shows that a narrow flow of water is essentially electrically nonconductive over two or three feet.
But with a basin full of water, a hot wire and a ground wire in the water at opposite ends will trip the GFCI.
The resistance of a basin of water measured 25k to 75K on my DVM depending on the range, and on the 20 megohm range it measured a negative value(???). So it sounds like the resistance of water depends on the voltage across or current through it. 25k at 120v could trip a GFCI.