Abstract: A filtration system is provided for a dry well in the form of a buffer tank made of concrete to remove sediment and pollutants from water supplied from a header to an inlet pipe in the tank, so that the water exiting from an outlet pipe is free of particulate matter and pollutants. This is accomplished by providing a sediment pit and a baffle at the inlet side of the tank and then passing the water through a multiple stage set of filters having different aperture sizes. These filters remove particles and pollutants from the water as it passes through the buffer tank on its way to a dry well drain pipe attached to the outlet of the buffer tank.