In Traditional Chinese Medicine (TCM), Shui Zhi belongs to the 'Herbs that invigorate the Blood' category. Like the name indicates these herbs tend to stimulate the Blood flow. In TCM they're used to help the circulation of Blood in cardiovascular conditions or menstrual irregularities as well as to treat acute pains caused by Blood Stagnation. They can also be used to treat Blood Stagnation when it causes certain tumors, cysts and hardened clots.
Furthermore Shui Zhi is Neutral in nature. This means that Shui Zhi typically doesn't affect the balance in your body. Balance between Yin and Yang is a key health concept in TCM. Eating too many "Hot" (Yang) ingredients can lead to an imbalance whereby one has a Yang Excess. The inverse is true as well: too many "Cold" (Yin) ingredients can lead to a Yin Excess. The Neutral nature of Shui Zhi means that you don't have to worry about that!
Shui Zhi also tastes Bitter and Salty. The so-called 'Five Phases' theory in Chinese Medicine states that the taste of TCM ingredients is a key determinant of their action in the body. Bitter ingredients like Shui Zhi tends to have a cleansing action on the body by clearing Heat, drying Dampness and promoting elimination via urination or bowel movements. On the other hand Salty ingredients tend to have a draining effect in the body because they clear accumulations, remove Phlegm and soften hard lumps.
The tastes of ingredients in TCM also determine what Organs and Meridians they target. As such Shui Zhi is thought to target the Bladder and the Liver. In TCM the impure water collected by the Kidneys that cannot be used by the body is sent to the Bladder for storage and excretion as urine. The Liver on the other hand is often referred as the body's "general" because it is in charge of regulating the movements of Qi and the Body Fluids. It also takes a leading role in balancing our emotions.