They can also breathe air and are able to go out and get a Coke or latte as the mood strikes. They were first reported by mystical dude Paracelsus in the Middle Ages, so water sprites have been waiting around for centuries to get their daily caffeine fix. This meant that they were always cranky in olden times and explains all the stories about humans being jerked around by water sprites.
Water sprites are not to be confused with mermaids, the difference being that mermaids have tits. However, if you ever encounter a water sprite returning from a 7-11, avoid the temptation of not maintaining eye contact and looking down to check out if the creature has hooters or not.