Distribution boxes are commonly used to equally distribute septic tank effluent (STE) among the trenches of septic systems. Various products are available for distribution boxes and to equalize flow among the outlet holes in the boxes. Although studies have demonstrated the ineffectiveness of distribution boxes, the products are still in widespread use. This study used concrete, plastic, and tipping bucket boxes. All of the products were tested with and without flow equalization devices inserted in the outlet holes. The plastic and concrete boxes were tested by dosing with a pump at various flow rates. The study shows that even if the distribution box is leveled to achieve equal distribution among the outlets of the box, very poor distribution is achieved along the discharge piping, even under pumped conditions. The results of the study demonstrate that distribution boxes are ineffective for distributing wastewater equally along the soil absorption trenches, even with dosing and with flow equalization products in use.