The Pentek S1-20 water filters reduce sand, sediment, silt, rust particles, and scale particles. The Pentek S1-20 filters have pleated walls for dirt-holding capacity. The Pentek S1-20 water filter media is pleated around a polypropylene core for added strength and the ends are immersed in a thermosetting vinyl plastisol. The Pentek S1-20 water filter cartridge has an external netted sheath that helps retain uniform pleat spacing in high flow and pulsating flow streams. The overlap seam is sonically welded to reduce bypass, improving filtration efficiency.