What do we use all this for? Of all the that falls to California, 60% is immediately returned to the atmosphere by evaporation or native plant use. The rest runs off into rivers, lakes, streams and the table, where it is available for human use. We will explain what happens to all this , show exactly how much we do use, and give ways to reduce use in and around your home. The single largest user of is industry. Industries use 46% of our annual supply. One industrial use is manufacturing, in various ways such as cooling of materials, ....