A pilot study was conducted to evaluate the Atlantic City Municipal Utilities Authority's (ACMUA) existing filtration facilities to determine the potential for increasing filtration capacity. The ACMUA has established a goal of upgrading their filtration facilities to allow for: additional capacity (increase from 18 MGD to 22 MGD); the ability to remove filters from service to perform maintenance; and, to meet a turbidity goal of 0.1 NTU at their filtration plant. Filtration theory, particularly the L/d (bed depth divided by the media diameter) and L/d³ ratios, was examined in order to design alternative filter media configurations. Traditionally, the L/d ratio has been on the order of 1,000 to 1,200. Recent filtration theory has shown particle removal is a function of the L/d³ ratio which is more dependent on media size (ES). The higher the L/d³ ratio the lower the initial filtered water turbidity. The pilot study tested three alternative media configurations along with a control column that was identical to the existing filter media configuration: control - 36" Filtrasorb 300 (0.9 mm ES) and 4" sand (0.5 mm ES); Alternative 1 - 36" Filtrasorb 300 (0.9 mm ES) and 12" sand (0.5 mm ES); Alternative 2 - 48" Filtrasorb 816 (1.4 mm ES) and 12" sand (0.5 mm ES); and, Alternative 3 - 48" Filtrasorb 820 (1.1 mm ES) and 12" sand (0.5 mm ES). The three alternative media configurations and the control were tested at a loading rate of 5.5 gpm/sf. The tests were conducted with four 4-inch diameter filtration columns operating in parallel. The flow treated by the filtration columns was taken from the top of the existing filters. Data recorded included turbidity, particle counts and headloss. The control filter column mimicked the full-scale plant. All three alternative configurations outperformed the control filter - that is, they produced filtered water with lower turbidity and particle counts, but longer filter run times. The pilot study results demonstrated that additional capacity could be achieved without constructing new filtration facilities. Renovation of the existing filters saved ACMUA millions of dollars in capital costs. The design of the upgrade of the existing filters was based on the configuration of the pilot filter system with the optimum filtered water turbidity, particle count and unit filter run volumes. The selected media configuration was 36 inches of 1.1 mm ES GAC over 12 inches of 0.5 mm ES sand. The new filters have a higher L/d³ ratio, thicker sand layer, new underdrain and upgrade in the backwash scheme including air scour and increased backwash rate. The first of six filter upgrades was placed in service in March 2007. Includes tables, figures.