One of the solutions to the problem of water conservation is to recycle wastewater. When you flush the toilets at Stensund Folk College near Stockholm, Sweden, you help teed the fish. The school treats the wastewater in a greenhouse, where it is then used to provide water to plants and fish in an integrated cultivation system. In Lima, Peru, ponds full of algae and other small organisms clean up the wastewater. After 20 days, it is safe for reuse. Currently many factories, hotel chains, and apartment buildings around the world are installing water recycling systems.