Storm Water runoff is generated when precipitation from rain and snowmelt events flows over land or impervious surfaces and does not percolate into the ground. As the runoff flows over the land or impervious surfaces (paved streets, parking lots, and building rooftops), it accumulates debris, chemicals, sediment or other pollutants that could adversely affect water quality if the runoff is discharged untreated.
In particular Storm Water is an issue in urban areas where impermeable surfaces such as asphalt, cement, and steel have replaced natural organic surfaces such as dirt and gravel. If you have ever been in a storm in a large parking lot of garage you can see hundreds of gallons of water running toward the nearest incline searching out nearest permeable surface, but more often than not finding a drain or sewer.
This situation, the removal of permeable surfaces can turn average rainfall into a flood that slowly dissipates into the sewer, never to recharge the groundwater supply nor irrigate what natural surfaces remain. The sole solution to this problem is to capture and store this water for redistribution during arid times.
Capture and containment of Storm Water is easily achieved using molded gutters in parking lots, slopes, drains, and pipe to deliver the water to storage tanks. The kind of tank required depends on route of delivery and inclines encountered. Underground Tanks work very well but Above Ground Corrugated Bolted Steel tanks are becoming increasingly popular.