A method of minimizing head loss in a filter system including a plurality of drop pipes, a plurality of filter cells having a maximum influent level, and a distribution box having a maximum influent level, a base, and a plurality of distribution cells. The method includes positioning a first end of each of the plurality of drop pipes within one of the distribution cells such that the first end of the pipe is disposed within the distribution cell and defines a weir having a weir height. The method further includes positioning a second end of each of the pipes in fluid communication with one of the plurality of filter cells. The method also includes supporting the distribution box such that the maximum influent level of the filter cells is above the base of the distribution box and below the maximum influent level of the distribution box.