Big Blue 20" Water Softener Cartridge by Pentek Part # 155321-43

Pentek® by Pentair® is a trusted name in water filtration products for residential, commercial, and light industrial applications. Known for dependable performance and broad compatibility, Pentek filters and housings are widely used to improve water quality, protect equipment, and support reliable point-of-entry (POE) & point-of-use (POU) water treatment systems.

Pentek's filtration lineup includes sediment, carbon, specialty, reverse osmosis, and deionization products along with industry-recognized housings and support components. From Big Blue & Slim Line housings to cartridge filters, RO membranes, and under-sink filtration systems, Pentek products are designed for practical installation, convenient maintenance, and consistent long-term service.

About Pentek® Filters, Housings & RO Components

Pentek filter cartridges are designed to address many common water treatment requirements including sediment reduction, chlorine taste and odour reduction, iron reduction, lead reduction, deionization, remineralization, and RO pre/post-filtration. Popular cartridge families include spun polypropylene sediment filters, string-wound filters, pleated cellulose polyester filters, carbon block filters, GAC filters, and specialty cartridges for scale inhibition, softening, and heavy-duty whole-house filtration.

The Pentek product range includes sediment filters, carbon block cartridges, granular activated carbon filters, radial flow cartridges, deionization filters, lead reduction cartridges, reverse osmosis membranes, undersink drinking water systems, and a broad variety of replacement housings and accessories. These products are available in Standard, Slim Line, Big Blue, inline, bag filter, and quick-change formats to support both low-flow and higher-capacity filtration applications.

Pentek housings and system components are equally well known throughout the water treatment industry. Big Blue heavy-duty housings are designed for large-capacity, high-flow, and heavy-sediment applications, while Standard and Slim Line housings offer practical filtration options for more compact residential and undersink installations. Pentek's comprehensive line of supporting products and accessories includes wrenches, O-rings, brackets, replacement baskets, membrane housings, and other service parts that help service professionals and DIYers keep existing filtration systems operating properly.

For reverse osmosis and drinking water applications, Pentek products include RO membranes, inline polishing cartridges, remineralizing cartridges, under-sink filtration systems, and FreshPoint replacement components. These systems and cartridges are commonly used to improve drinking water quality in homes and specialty applications where reliable filtration, convenient maintenance, and compact installation are important.

If you are looking for a specific Pentek® filter cartridge, filter housing, RO membrane, FreshPoint replacement part, or installation accessory not listed on this page, please contact us by email or call our office (1-866-489-4004) for assistance. We supply genuine Pentair Pentek products and can help you identify the correct cartridge, housing, or component for your water filtration or reverse osmosis system.

Browse our full selection of Pentair Pentek filters, housings, membranes, and accessories and get dependable water treatment components shipped FAST from our Canadian warehouse DIRECTLY to your door. A real Water Guy can help you select the right Pentek solution for your residential, commercial, or specialty water filtration application.