Distribution Box Diversion Test

A Distribution Box Diversion Test evaluates whether a septic system's D-box evenly distributes effluent to all drain field lines, identifying clogs, tipping, or flow imbalances.Purpose of the TestThe test ensures that wastewater from the septic tank is evenly distributed across all drain field lines. Uneven distribution can overload one section of the soil, causing pooling, slow drainage, foul odors, or premature drain field failure. A diversion test helps detect clogs, tipping, or structural damage in the D-box before serious system problems occur .Locating the Distribution BoxConsult system diagrams: “As-built” plans or septic blueprints indicate the exact location and depth of the D-box .Follow the outlet pipe: If diagrams are unavailable, the D-box is usually in a straight line from the septic tank's outlet baffle .Probe the ground: Use a metal soil probe to locate the hard, flat lid of the buried box .Performing the Diversion TestOpen the D-box lid carefully to inspect for debris, tipping, or damage .Pour water into the system: Introduce a measured amount of water into the D-box and observe how it flows into each lateral drain line .Check flow distribution: Ideally, water should exit evenly through all outlets. Uneven flow indicates a tilted box, clogged outlet, or misaligned weir .Adjust outlets if needed: Some D-boxes have adjustable weirs or plugs that can be raised or lowered to balance flow among lines, compensating for slight tilts or differences in line length .Maintenance and TroubleshootingClear clogs: Remove debris from the D-box and lateral lines to restore even flow .Level the box: Ensure the D-box is properly leveled to prevent preferential flow .Inspect for leaks or cracks: Repair or replace damaged boxes to maintain system efficiency .Regular checks: Periodic inspection prevents drain field overload and prolongs system life .Key ConsiderationsSoil type affects flow and may require adjustments in D-box placement or outlet configuration .Pumped systems may need additional attention to ensure the pump delivers effluent evenly to the D-box .Multiple outlet D-boxes allow diversion to different drain fields, which is useful for system expansion or maintenance . A properly conducted Distribution Box Diversion Test is essential for maintaining a healthy septic system, preventing backups, and ensuring the longevity of the drain field.