In multiple compartment fiberglass septic tanks, what is the minimum capacity required for the first compartment?

The minimum capacity required for the first compartment of a multiple compartment fiberglass septic tank is specifically set at two-thirds of the total tank capacity. This design standard is rooted in the functionality and effectiveness of septic systems in managing and treating wastewater.

Having two-thirds of the total capacity in the first compartment allows for sufficient retention time for solids to settle and for initial treatment processes to occur. This is crucial, as the first compartment acts as the primary wastewater treatment area where larger solids are separated and settled out. A larger capacity ensures that the tank can handle peak flow rates and variations in wastewater input while maintaining effective treatment.

This ratio also helps to balance the flow into subsequent compartments, allowing them to function efficiently without being overloaded with solids or wastewater. The correct distribution of tank capacity across compartments contributes to overall system effectiveness, ensuring that the treated effluent can be adequately processed in the additional compartments before being discharged into the drain field.