With the global population at about 7.5 billion, and each human theoretically needing 2 liters of drinking water, there is a demand for 15 billion liters of water each day to meet the minimum requirement for healthy living (United).
全球约人口75亿，每人理论上喝2升水，那么每天最少要150亿升水来维系健康生活（美国）。