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What is a Septic Distribution Box

RCI Septic Service • February 17, 2023

The distribution box, commonly known as D-box, is another important part of your septic system. The main function of the D-box is to distribute effluent (wastewater) evenly to the leach field or drain field.


The D-box is a rectangular box, placed between the septic tank and leach field, has an inlet pipe and several outlet pipes to evenly distribute the effluent to the drain field. D-boxes have different amounts of outlet pipes for different size fields. They are made of concrete, plastic or fiberglass.  Concrete is more rugged than plastic but can deteriorate over time where as plastic would not. The system design will dictate which type of D-box will be placed and the number of outlets needed.


The D-box could crack or get damaged over time due to weather or other unforeseen circumstances. When a D-box is damaged it doesn’t allow water to go into the leaching field and can fail the dirt around it. It should be repaired as soon as possible, once fixed the rest of the field should still function properly.

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