Why black water?

Because the five elements theory holds that the five elements are wood, fire, earth, gold and water.

Five directions: southeast, central and northwest.

Facial features: eyes, tongue, nose, mouth and ears.

Five colors: cyan, red, yellow, white and black.

The patron saint of the East is Qinglong (cyan); The patron saint of the west is the white tiger (white);

The patron saint of the south is Suzaku (red); The patron saint of the north is Xuanwu (black).

So black in the five elements belongs to water. Doctor yang