A leach pit is a secondary system that is used to treat and dispose of the effluent from a bio septic tank. The leach pit is typically made of concrete  and is designed to allow the effluent to seep into the soil. The leach pit is an essential accessory for a bio septic tank, as it helps prevent the accumulation of effluent in the drain field. It consists of two or more chambers, with the inlet and outlet pipes connecting them. When wastewater from the house enters the tank, the solids settle to the bottom, and the liquid flows into the second chamber, where it is further treated and filtered.

The liquid is filtered by a process called anaerobic digestion, where bacteria break down the organic matter in the wastewater. The resulting effluent is then allowed to flow out of the tank and into the surrounding soil through a system of perforated pipes or leach field.One of the main benefits of using a leach pit is its ability to improve the efficiency of a bio septic tank. The leach pit helps distribute the effluent more evenly, which reduces the risk of clogging and overflow. It also helps prevent the contamination of groundwater, which can cause environmental damage.