Going by the Forbes article’s numbers on adult human water consumption, 6.6 billion m^3 would be pretty damn close to the entire human population’s water needs. 2.6 litres per adult per day is 0.949 m^3 over a year, so multiplying that by a world population of 8.2 billion people (I know that’s adults and children but I’m approximating for scale here) is 7.7 billion m^3 of fresh water
Going by the Forbes article’s numbers on adult human water consumption, 6.6 billion m^3 would be pretty damn close to the entire human population’s water needs. 2.6 litres per adult per day is 0.949 m^3 over a year, so multiplying that by a world population of 8.2 billion people (I know that’s adults and children but I’m approximating for scale here) is 7.7 billion m^3 of fresh water
2.6L/day might cover drinking water, but definitely not cooking/cleaning/bathing/laundry. Let alone growing food.