Pervious paving allows water to infiltrate into layers of crushed rock placed below the paving and then into soil and groundwater below. By infiltrating most of the storm water on site, the amount of water and pollution flowing into storm sewers and directly to rivers and streams is greatly reduced. This protects water quality, maintains more stable base flows to streams, reduces flood peaks, and reduces stream bank erosion. With infiltration, groundwater is recharged and streams are replenished with cool, clean groundwater in a more natural way. Pervious paving is one component of Low Impact Development (LID).
Depending on the site, pervious paving systems may result in significant savings by eliminating required retention and detention ponds and reducing the need for conventional storm sewers.