He that was divine took on a human nature. He became the water and the Blood. These are basic life forces. Water is the essence of what we are made of, the natural elements God has poured into us. Water is taken in on a daily basis to prevent our dehydration.
Man can go forty days without food but only three days without water.
It is a necessity of life. So is the word of God. The washing of the word renews our minds, giving us strength, encouragement, and direction. The word sustains us. Jesus became as we are, and in His death, the Blood and the water poured out.