GEF

Unit 5  |  Toward Sustainable Water Systems 130 business. Although normally of high quality, rainwater may contain atmospheric pollutants and other chemicals which make it inappropriate for drinking water. Some systems, however, filter and treat rainwater in order to supply potable water. More and more, rainwater harvesting is seen as an attrac- tive and cost-effective approach to meeting local water needs in locations around the world. In Singapore, which has a large population and limited freshwater resources, architects installed a rainwater harvesting structure at the main airport. In this system, rainwater falling on runways and surrounding green areas is diverted into catchment basins, providing water for uses such as firefighting and toilet flushing. In Hawaii Volcanoes National Park, a large system harvests rainwater from the roofs of several park buildings. The rain- water is filtered, stored, and distributed as a water supply for park residents, workers, and employees. Without the option of drilling wells in the volcanic topography of this remote region, rainwater harvesting offers a vital drinking water source. A rain barrel is one method individuals can use to harvest and store rain water for uses such as watering plants. POTABLE Water that is suitable for drinking.