Impervious surface

An impervious surface is like a raincoat for the ground. Just as a raincoat keeps you dry, an impervious surface keeps the ground underneath it dry by not letting water pass through it. Imagine you are playing outside on a really rainy day, and you have a big umbrella to stay dry. Now imagine that instead of an umbrella over your head, you have a hard plastic sheet on the ground that rainwater cannot seep through. This is what it means to be an impervious surface. Common examples of impervious surfaces include roads, driveways, parking lots, and sidewalks. When rainwater falls on these hard surfaces, it runs off and does not sink into the ground, potentially causing problems with flooding and pollution of nearby waterways.