The Water Element is a quest item from The Minish Cap.
The Water Element is one of Four Elements that Link acquires in The Minish Cap. It is the third element found, located in the Temple of Droplets within Lake Hylia. Along with a Heart Container, it is the primary reward for defeating the Big Octorok and clearing the Temple of Droplets.
After Link acquires the Water Element, he can then travel to the Elemental Sanctuary. This time he'll need to enter through a secret entrance at the west side of the Hyrule Castle Courtyard. Link can fuse the third element with the White Sword, turning it into the White Sword (Three Elements). This will allow Link the ability to split into three.