Where does the rest of the water go?
Do you know what happens to the rainwater that doesn't evaporate or soak into the ground? Some of it flows over hard surfaces (like roofs, parking lots, driveways, sidewalks, roads, etc.) and into the nearest storm drain, stream, or ditch. This water is called "runoff" or sometimes "stormwater runoff." Storm drains look like big grates in the road where water "disappears" when it rains. These storm drains carry water underground directly into your local streams without being treated.
As this water flows over our hard surfaces, it picks up harmful pollutants that we have left behind. Pollutants are anything harmful to our natural resources. Sometimes the pollution is something you can see like trash, oil, soap, and dirt. Other times you can't see the pollution at all, like when chemicals, bacteria, pesticides, and fertilizers are washed into a nearby creek.