Water is the most significant symbol in the Tao. (The Tao is the foundation of Chinese Medicine.)

“The highest goodness resembles water.”

Every organ has an element and water is assigned to the Kidney. Dreams, more specifically nightmares about water are a sign of Kidney pathology.

The kidneys are believed to store all the energy you will have in life so their health is crucial.
Kidney pathology presents 1st and foremost with any sexual dysfunction; impotence, low libido and infertility. Other symptoms are low back and knee pain, tinnitus and trouble concentrating. 

The kidney is weakened by excessive fear, drugs and medications, especially stimulates like Adderall and diet pills, excessive masturbation, poor diet and poor hydration.
Strong kidneys present as good leadership skills, confident decision making, bravery, sexual stamina and a strong back.