A storm drain, storm sewer (U.S.), stormwater drain (Australia and New Zealand) or surface water system (UK) is designed to drain extra rain and ground water from paved streets, parking lots, sidewalks, and roofs. Storm drains vary in design from small residential dry wells to large municipal systems. They are fed by street gutters on most motorways, freeways and other busy roads, as well as towns in areas which experience heavy rainfall, flooding and coastal towns which experience regular storms.