1. This system consists of a septic tank, constructed wetland, and land application system. The wetland consists of a bed of graded stone with water flowing just below the surface. Vegetation that is adapted to saturated conditions is grown in this bed, feeding on the nutrients, organic matter, suspended solids, and pathogens in the effluent. The bed is set in a watertight basin lined with compacted native clay, bentonite clay, concrete, PVC, or a similar watertight substance. Although both hard- and soft-tissue plants can be used in the system, some experts prefer hard-tissue plants believing they provide a pathway for oxygen to enter the wetland during winter months and hard-tissue plants reduce maintenance. However, many homeowners prefer colorful, flowering, soft-tissue plants.