A distribution box (d-box) is a small concrete or plastic box installed between a septic tank and drain field that divides outgoing effluent equally among multiple leach lines. Without it, wastewater would flood one section of the drain field while starving others, causing premature. Main Switch: This is the primary control point for the entire electrical system, allowing the entire system to be shut down quickly in an emergency or for maintenance. It acts as a flow divider, ensuring wastewater is evenly distributed into the multiple pipes of the drain field. They are designed to treat and dispose of sewage and wastewater on-site, providing an effective solution for areas where traditional sewage systems are impractical.