Global water resources contain a variety of organic chemicals, including pharmaceuticals, personal care products, and pesticides at trace concentrations. This study investigated the application of biofiltration for the removal of these so-called micropollutants from drinking water resources. The objective of this work was to examine how hydrodynamics influence biotransformation rates in biofiltration processes. Measurements included biomass concentration, depths of the biological zone, and removal rates of 29 micropollutants at environmentally-relevant concentrations in bench-scale biofiltration columns operated under three distinct hydrodynamic regimes. Higher superficial velocities led to less concentrated surface biomass but a deeper biological zone and more total biomass. Eleven micropollutants underwent biotic removal and second-order rate constants were not significantly different between hydrodynamic regimes for each micropollutant. Of these micropollutants, five had significantly greater second-order rate constants at deeper biofilter depths. This work is an important step in improving our understanding of how hydrodynamics influence drinking water biofiltration performance.