The study looked at data from 27 countries between 1960 and 2010 to see how urban water use changes with economic growth. They found that as countries get richer, urban water use first goes up, then down, forming an N-shaped pattern. This relationship is called the cubic water Kuznets curve. The researchers also discovered that water policies can affect how much water cities use. This means that by making the right policies, developing countries can grow their economies while using less water per person.