Distribution Boxes

A Key Component of any Sewage Disposal System
The distribution box, or D-box, is a key component of any sewage disposal system. Effluent (wastewater) leaves the septic tank and enters the distribution box, where the effluent must be evenly divided and discharged to the leaching system. It is critical that they are set level to prevent unequal distribution, which is a main factor of failed leach fields. Polylok© equalizers can be used to equalize an uneven D-box. The easiest way to test for levelness is to add water to the D-box.

For the system to function properly, all discharge pipes must receive equal amounts of effluent. If the fluid flow is unequal or inconsistent, the effluent will not be uniformly distributed throughout the leach field. One section of the leach field will receive effluent in excess of the design amount, while another section will receive little or no effluent. Distribution boxes are sometimes used to monitor the effluent going to the leach field.

Available in Five Sizes
To complement our full line of septic tanks, A.J. Foss offers six sizes of precast concrete distribution boxes, ranging from 5-outlet boxes to 28-outlet boxes.

  • Small Distribution Box: 5 Outlets: 2 Outlets on each side, 1 Outlet on the end
  • Medium Distribution Box: 7 Outlets: 3 Outlets on each side, 1 Outlet on the end
  • Large Distribution Box: 10 Outlets: 4 Outlets on each side, 2 Outlets on the end
  • XL Distribution Box: 14 Outlets
  • Commercial Size Box: 28 Outlets

View Distribution Box Sizes

H-20 Distribution Boxes Available
We also carry H-20 Distribution boxes for use below driveways, parking lots, and traffic areas. They are available in 14 Outlet, 18 Outlet, & 24 Outlet sizes. Please contact us for exact dimensions available.

Plastic distribution boxes are also available; please contact us to discuss your project.

  • 6-Hole Distribution Box
  • 9-Hole Distribution Box

Polylok Dipper Box Is Available

  • Guarantes uniform, equal dosing 
  • Equal Distribution to each outlet
  • Maintenance-free
  • As easy to install as a regular d-box      

Formed With High-Quality Concrete
Our team crafts each precast concrete distribution box using high-quality 5,000 psi concrete that is regularly tested using ASTM C31 and C39 quality testing guidelines. Our Type III high early strength cement is also tested monthly to ensure that it complies with ASTM Standard C 150 and AASHTO M 85 requirements.

We use Polylok© Low Pressure Pipe Seals in our distribution boxes. These seals require no sealing or mortaring, and accept pipe from two to four inches. Also, several pipe classes will work including: Schedule 40, sewer and drain, and SDR 35 pipe.

Contact us to discuss your projects throughout New Hampshire, Maine and Northern Massachusetts that require wastewater and stormwater products, and discover the A.J. Foss difference for yourself.

Distribution Boxes PDF Files