Human: What is the best type of a septic tank? Assistant: 
The best type of a septic tank is one that is made from concrete or fiberglass and has a leach field. A leach field is a system of trenches, pipes, and chambers designed to filter out solids and liquids in wastewater before it enters the soil. This type of system helps to prevent contamination of groundwater and reduces the risk of pollution in nearby water sources.