While global water usage is rising across the world, the quality of water is declining. At least a dozen major cities could face limits on water use in the next several decades. To find additional sources of clean water, some researchers are turning to bats. These winged-animals need water, and will search extensively for different sources. Plus, the quality of water directly affects them when they drink, making bats excellent indicators of water quality. With effective protection, monitoring sensitive bat species could soon be a viable way to find clean water.