From the drain, it goes into our septic tank deep in our yard, or into the sewer. From the septic tank, it soaks back into the ground. If it is in the sewer, it will come out somewhere, like the ocean or a sewage pond. Then it will evaporate again, and it will fill up the clouds again. When the clouds are full, it will rain again.
Rain water is clean and pure.
As it soaks into the ground or is evaporated, it is cleaned by the ground or the air. Fill a glass about half full of water. Cover the glass tightly with some plastic wrap. Put a rubber band around the glass to hold the wrap in place. Make sure there are no holes in the wrap over the top of the glass.