The report reviews use of filtering materials in diatomaceous earth (DE) filtration, slow sand filtration, and coagulation-rapid rate filtration. For DE filtration, increased effluent clarity (lower turbidity) is generally attained at the expense of increased rates of head loss increase. Changing the surface characteristics of DE from electronegative to electropositive permits use of coarser grades of DE for effective removal of fine particles. An important consideration in selecting media for slow sand filtration is whether to use media mined and prepared by a filter media processor, or whether to use a locally quarried and processed material as filter media, based on pilot plant studies of the filter media being considered and the source water which will be treated at the full scale plant. Trends in filter media design for plants employing coagulation and rapid rate filtration have varied over the decades. Recently a 600 MGD direct filtration plant was built with very deep beds consisting of a single medium anthracite. Filter bed design is continuing to evolve and change.