Check for any signs of damage, wear, or overheating in electrical panels, switchgear, transformers, and other equipment. A septic distribution box, often called a D-box, is a small, buried container that acts as a junction point between the septic tank and the soil absorption area. The box's primary function. Open the distribution box and check for dust and debris accumulation. Inspect circuit breakers for proper operation. When it fails, symptoms include uneven wet spots in the yard, slow indoor drains, and sewage odors.