Human, body is a better conductor than fresh water. It is your skin that usually offers a lot of resistance to electric current. But, if submerged in water this resistance is pretty much completely removed and the current chooses to run through the body. Many people have sustained injuries or died in accidents like that.
Breaker/fuses don't trip/blow fast enough. They are not designed to protect human live.
Special equipment exists for this purpose. A person can have a severe cramp, heart or respiratory problem or die before the circuit is broken.
Be sure before you post stuff like that!