Green Plumbing

Answer: A - There is no such thing as a terraced grid system; it is therefore not an alternative to the standard on-site wastewater treatment system. A recirculating sand filter (RSF) system adds the extra step of passing waste through a sand filter prior to eventual movement to the drainfield. A mound system involves creating an elevated drainfield where a traditional drainfield would not provide sufficient soil and water table depth. An aerobic treatment unit (ATU) system, unlike a traditional septic system, uses oxygen to treat wastewater.