Gravity separation is the most straightforward method of wastewater treatment and is, therefore, utilized widely in industry for separation of settling and/or floatable impurities from a carrier liquid.

An enlarged separating surface can be achieved by placing various smaller planes on top of each other in the tank. If these planes are subsequently inclined in a tilted position, material separated between the plates is removed by the gravitational force. This is the principle on which the CPI corrugated plate pack is based.