What are the three elements of human life and health?

Water, air and food are the three elements of human life and health. 50% ~ 60% of human body weight is composed of water, and the water content in children is as high as 80%. It can be said that there is no life without water. However, the fresh water resources on the earth only account for 2.5% of the total water resources on the earth, of which only 0.26% is available for direct drinking. Therefore, water is a precious resource for human beings and the source of life.