A system and method for uniformly distributing fluids (e.g., washing and in-service) through a filter bed of a filter. The system and method of the present invention can be used with any type of filter that uses media to remove impurities from a fluid. The filter bed can include one or more layers of media. The media can be natural (e.g., sand, gravel, anthracite, etc.) or can be fabricated (e.g., plastic). The filter media can be supported by one or more layers of gravel. Alternatively, the filter media can be supported by a porous plate or other support designed to replace the gravel layers. The present invention includes a system having a distribution member configured to uniformly distribute a fluid through a filter bed of a filter. Preferably, the distribution member can be readily installed by relatively unskilled labor in both existing filters and new filters. The distribution member is preferably configured to occupy only a small percentage of space in a portion of the filter system (e.g., a flume, a filter compartment or other suitable location of the filter system). In retrofit applications, the design of the distribution member is such that no significant alteration of the filter system or fluid velocity is necessary. Preferably, the distribution member includes one or more plates. The plate or plates are designed to create a uniform piezometric head at each portion of the underdrain regardless of how far a given portion of the underdrain is from the fluid inlet in the distribution chamber. A single plate can extend substantially the length of the distribution chamber. Alternatively, a single distribution plate may extend across only several portions of the underdrain (e.g., several underdrain laterals) leaving one or more portions of the underdrain (e.g., one or more laterals) unaffected by the distribution plate. Further, a plurality of plates can be arranged in a side-by-side fashion to extend substantially the length of the distribution chamber. Preferably, the design of the plate or plates allows them to be mass produced.