Elkay 51300C_24PK WaterSentry Plus Replacement Filter (Bottle Fillers), 24-Pack Multi-pack replacement filters for models with WaterSentry Plus filtration system (Bottle Fillers). Filter should be replaced every 3,000 gallons or 1 year after installation. Equipped with Quick-Disconnect, 1/4 turn installation, as well as automatic inlet shut-off valve that closes when filter is removed. Designed to reduce lead, particles and chlorine. Also reduces odors and discoloration from incoming water. Spun Polypropylene prefilter mesh to prevent large, coarse sediment and particles from entering and clogging filter media. Filter is certified to NSF 42 and 53 for lead, particulate class 1, chlorine, taste and odor reduction.