The study looked at how much water people use in cities compared to how rich their country is. They found that as countries get richer, people use more water at first, but then they start using less when the country reaches a certain level of wealth. This is because as countries develop, they become more efficient with their water use. The peak point where water use starts to decrease is around $33,000 per person. This happens because of better technology, higher water prices, and laws that protect the environment. Developed countries show that this trend is possible for other countries too, especially as they grow economically.