The conducting abilities of water depends on the type of water or the purity of it. Pure water, that does not have any other elements in it is a better insulator of electricity than it is a conductor. The opposite holds true for things like salt water, because of the extra elements in it.
The fact that salt water is a good conductor of electricity affects the human body. The human body is mostly made up of saltwater, which means that a person's body is a good conductor of electricity. This is one reason that humans are sometimes hit by lightening strikes or they can build up static electricity with the socks on their feet and transfer it via contact to someone else and shock them.