For several years, research has been conducted on ripening and breakthrough in carefully-controlled filtration experiments. These experiments were first performed with latex suspensions (monodisperse and mixtures to obtain polydisperse suspensions), and subsequently with two types of heterodisperse suspensions found in water treatment plants: lake water (contact filtration for drinking water) and conventional drinking water (post-sedimentation water from a lime-softening plant). Throughout this research, the goals were to understand how particles of different sizes were affected by ripening and breakthrough, and how these phenomena were influenced by the major variables of filtration design and operation, including media size, media type (spherical glass beads and commercial filter sand), media depth, and filtration velocity. Results from several individual components of this work such as latex, contact filtration, and softening plant water, have been published. The objective of this paper is to present a synthesis of this extended research, with some emphasis on the most recent part of the research, that done with sand media.