Sheesh guys! lol.
The water analogy works for a very basic understanding of electricity. It works ok for the most part when dealing with DC, but falls apart very quickly with AC. And our ESCs running pulsed DC is effectively AC (no one said AC has to be a sine wave). So, it is very difficult to use the whole water example effectively.
In short, water pressure=voltage, restriction in a hose=resistance, water flow=current. That's about all you can do.
Slim: Actually, if you think about it. Water would "jump" from a cup if enough pressure is present. It would either blast a hole in the bottom (signifying breakdown of the "insulator" which is what happens with HV), or splash out.