At present in the United States, people use about 1,500 gallons a day for their needs and comforts including recreation, cooling, food production, and industrial supply. When water hits the ground some soaks into the soil, and the rest runs off over the surface. The water that soaks into the soil sustains plant and animal life in the soil. Some seeps to underground reservoirs. Almost all of this water eventually enters the cycle once more.
People can alter the water cycle but little, so their primary supply of water is firmly fixed.
But we can manage and conserve water as it becomes available when it falls on the land. If we fail to do so we lose the values that water has when used wisely. Water management begins with soil management. Because our water supply comes to us as precipitation falling on the land, the fate of each drop of rain, each snowflake, each hailstone depends largely on where it falls on the kind of soil and its cover. This action, soil erosion by water, repeated many times ruins land for most uses.