Recent anthropological studies and excavations have revealed that the Mayans, 800 BC to 100 AD, constructed an extensive water system. As an agrarian society in a tropical climate that teetered between overly wet and drought, the Mayans designed a solution. They created an elaborate water system replete with channels, wells to store water collected during the wet months, dams to gradually ration water during dry months, sluice gates to better control water distribution and switching stations that controlled the directional flow of water. It is also believed that they developed a rudimentary but effective filtration system using sand to sift their various water supplies. Their calendar may have been off but their water system was right on track !