I just dont buy the simple water theories. The water-carrying capacity of a fuel is finite and varies with temperature.
AFAIK the tests have not been able to reproduce the fault without direct injection of water, a situation that would not occur in real life. I am not a conspiracy theorist but I am convinced there is something else fuel related going on.
PS "hot hydrant" doesnt mean "hot" or "warm" in the temperature sense. It simply means that the fuel is continually under positive pressure in the fuel trunk line to the apron service points, in the same way that your house electricty sockets /outlets are "hot" or "live" all the time. Keeping it this way prevents water and dirt entering the fuel line although it does mean that there is an increased risk of fuel leakage which is why there are (or should be) leak detection systems running along the pipe conduit.