Next to air, water is the most essential substance to life. Our bodies are composed largely of water and we are not able to tolerate even the loss of 10% without serious degradation in the function of everything from the brain to the blood. Water is a hydrant, a lubricant, a solvent, and a cleaning agent.
Outside of the body, we use water to bathe, washing toxic substances from the body. We also use water in our worship of God symbolically in baptism and repentance. A good bath is as good for the soul as it is for the body. It does not redeem us, but is an act of faith toward cleansing.
Water also has the ability to redirect the flow of blood in our bodies by its ability to transfer heat into or out of portions of the body. Blood flow follows these temperature changes. This Hydrotherapy has been known and used for centuries. It is surprisingly effective in healing.