Without water, there is no life. So protecting this valuable resource should be at the top of everyone’s list. The supply of freshwater may seem endless if you have access to clean water. But what do you really know about the Earth’s water supply and what condition it is in? How much do you know about the hydrologic cycle—the amount of water used at home, in factories, in energy production or in agriculture? Do you know how water shortages develop or how to protect the health of natural ecosystems so they can sustain life today and for future generations? Take the following quiz to put your water knowledge to the test.