A reservoir in Finland pumps water from the underground that is so pure it doesn’t require any treatment to make it potable. The natural reservoir is vast enough to serve as the prime water source for as many as 150,000 people. In order to prevent its over-exploitation, scientists have developed a system that monitors the water levels and sends real-time feedback back to them. This novel technology could soon be used to extract water more sustainably and prevent resource depletion.