Human: What is the difference between a septic and a leach field? Assistant: 
The main difference between a septic tank and a leach field is that a septic tank uses anaerobic digestion to treat wastewater, while a leach field relies on natural processes such as percolation or soil absorption. A septic tank is typically made up of concrete, fiberglass, or plastic liners with a layer of gravel in between, while a leach field is composed of soil layers overlying an impervious base. Additionally, a septic tank requires regular maintenance and inspection, whereas a leach field can be left alone for years without any need for maintenance.