Get cleaner, clearer, better tasting water right at your sink with the Pentair OMNIFilter CB1 carbon block replacement cartridge. It reduces chlorine taste and odor along with fine sediment and rust particles, so your drinking water, coffee, tea and ice taste crisp and fresh. The CB1 is a dense 0.5 micron carbon block made using an extrusion process for superior flow rates and chlorine reduction. It is NSF and ANSI Standard 53 certified to reduce cysts such as Cryptosporidium and Giardia by mechanical means, and it works on both chlorinated city water and non-chlorinated well water. With a 400 gallon capacity, it is ideal for under sink drinking water systems and also makes an excellent polishing or pre-filter where fine filtration is needed. The CB1 fits Pentair OMNIFilter CBF1, CBF3, OT32 and USM2 under sink systems and also fits 10 inch by 2.5 inch under sink housings from many other major brands, so it can replace most standard carbon block cartridges of the same size. Plan on a fresh cartridge about every 6 months, or sooner if you notice reduced flow or a change in water taste or quality.