How many gallons must the lowest liquid level (pump off) be in the minimum size septic tank?

The minimum size septic tank must have a lowest liquid level (pump off) of 1000 gallons to ensure proper functionality and compliance with health and safety standards. This volume allows for adequate retention time for solids to settle and for biological treatment to occur, which is crucial for the effective breakdown of waste materials.

A tank with this capacity helps prevent issues such as pump cycling, which can happen if the tank is too small to handle the inflow of wastewater. Additionally, having a larger tank can accommodate variations in water usage, ensuring that the system can handle peak loads without compromising treatment. Overall, the regulation of a 1000-gallon minimum size establishes a standard that not only optimizes the septic system's performance but also protects the environment by reducing the risk of system failure and contamination.