Distribution boxes act as important junctions, ensuring uniform effluent distribution to prevent system overload. Signs of issues include odors, slow drainage, and standing water. Regular inspection and maintenance are key. However, in actual applications, distribution boxes often encounter a series of problems, which not. How Severe is Impact Damage on an Enclosure? Physical impacts alter the alignment of sealing gaskets and create micro-cracks in heavy-duty enclosures. Even a minor 5-joule mechanical strike can breach the strict IP65 or IP66 ingress protection ratings of an outdoor weatherproof box. Drain. In this guide, I have discussed ten of the common problems with a septic tank distribution box (D-box) and how to fix them.