--- product_id: 439736822 title: "Pentair Pentek WS-20BB, 20\" Big Blue Water Softener Cartridge, 20\" x 4.5\" | Sodium-Form Cation Resin Reduces Hard Water Scale in Pipes and Appliances, 4,500-Grain Capacity" brand: "pentek" price: "1702.97 DT" currency: TND in_stock: true reviews_count: 5 category: "Pentek" url: https://www.desertcart.tn/products/439736822-pentair-pentek-ws-20bb-20-big-blue-water-softener-cartridge store_origin: TN region: Tunisia --- # 4,500-grain softening capacity Fits all 20" Big Blue housings Optimized ion exchange resin Pentair Pentek WS-20BB, 20" Big Blue Water Softener Cartridge, 20" x 4.5" | Sodium-Form Cation Resin Reduces Hard Water Scale in Pipes and Appliances, 4,500-Grain Capacity **Brand:** pentek **Price:** 1702.97 DT **Availability:** βœ… In Stock ## Summary > πŸ’§ Upgrade to the Big Blue standardβ€”because your water deserves elite softening. ## Quick Answers - **What is this?** Pentair Pentek WS-20BB, 20" Big Blue Water Softener Cartridge, 20" x 4.5" | Sodium-Form Cation Resin Reduces Hard Water Scale in Pipes and Appliances, 4,500-Grain Capacity by pentek - **How much does it cost?** 1702.97 DT with free shipping - **Is it available?** Yes, in stock and ready to ship - **Where can I buy it?** [www.desertcart.tn](https://www.desertcart.tn/products/439736822-pentair-pentek-ws-20bb-20-big-blue-water-softener-cartridge) ## Best For - pentek enthusiasts ## Why This Product - Trusted pentek brand quality - Free international shipping included - Worldwide delivery with tracking - 15-day hassle-free returns ## Key Features - β€’ **Scale-Busting Power:** 4,500 grains of sodium-form resin to obliterate hard water scale and protect your pipes and appliances. - β€’ **Durable & Leak-Proof:** Polypropylene endcaps and Buna-N gaskets guarantee a secure, mess-free seal in heavy-duty housings. - β€’ **Effortless Maintenance:** Single-use design with clear replacement indicators keeps your water soft and your routine simple. - β€’ **Precision Ion Exchange:** Engineered for optimal water-resin contact ensuring maximum hardness reduction at recommended flow rates. - β€’ **Universal Fit, Zero Hassle:** Seamlessly replaces any 20" x 4.5" Big Blue cartridge for instant upgrade without remodeling. ## Overview The Pentair Pentek WS-20BB is a 20" x 4.5" Big Blue water softener cartridge featuring a 4,500-grain sodium-form cation resin capacity. Designed for low flow applications up to 2.0 gpm, it reduces hardness minerals and scale deposits, protecting plumbing and appliances. Compatible with all standard 20" Big Blue housings, it offers a durable, leak-proof seal and a single-use cartridge style for easy maintenance and reliable performance. ## Description The Pentair Pentek WS-20BB water softener cartridge is engineered to reduce hardness minerals from your water supply using sodium-form cation exchange resin. Hard water causes scale deposits that restrict flow in pipes, leave spots on fixtures and glassware, and shorten the service life of water heaters, dishwashers, and other appliances. This cartridge addresses those problems with 4,500 grains of softening capacity in the industry-standard Big Blue 20" x 4.5" format.The WS-20BB uses 20 x 40 mesh cation resin held in place by polypropylene pre-filter and post-filter layers that prevent resin from entering your water lines. Polypropylene endcaps and Buna-N gaskets ensure a proper seal within compatible Big Blue housings. An internal expansion pad accommodates resin movement during operation, maintaining consistent performance from first use through end of service life.This is a single-use cartridge designed for point-of-entry or point-of-use cold water applications between 40-100 degrees F. For optimal hardness reduction, maintain a flow rate at or below the recommended 2.0 gpm (8.5 Lpm) to allow sufficient resin contact time. Replace the cartridge when hardness levels in treated water begin to rise. Review: They really work - I was skeptical about this filter. I feared that (1) it wouldn't filter well, or it would have a reduced flow rate compared to the activated carbon filter that we were using. And (2) I feared that the "water softening" claim would be a gimmick of some sort. However, I am very pleased that this filter performs as claimed. The flow rate is slightly higher than the pleated/carbon filters that we replaced. The filtering is fine, with no noticeable increase in solids. And the filtered water is actually soft. We can lather in the shower; the dishwasher actually works now; the clothes washing machine produces better results. I will buy these again -- this is now our preferred filter. We live in northeast Wyoming right next to a creek. Our well is only 20 feet deep, and we are basically drinking creek-water. So, we depend on the big blue filter and a UV-lamp system to make our water potable. With activated carbon filters and the UV system, we were safe. But the water was very hard. We don't have room for a traditional water softening system without major remodeling. So, this filter provides a convenient upgrade. Yes, the filters are expensive, but in my opinion, they are a good value. Review: Four Stars - Great price, remove most but not all mineral from water. ## Features - CARTRIDGES USE a sodium based, non-solvent rinsed softening resin to reduce hardness, minerals and scale deposits in low flow rate applications - FITS ALL 20" Big Blue or other heavy duty housings and can replace any 20" x 4.5" water softener cartridge - CARTRIDGE STYLE DESIGN PROVIDES A CONVENIENT SOLUTION for delivering softened water to protect sensitive water delivery equipment - DESIGNED TO ALLOW OPTIMAL CONTACT between water and resin surfaces, ensuring maximum ion exchange - 4,500 GRAIN CAPACITY. Cartridge utilizes single-use resin technologies for maximum life grains capacity ## Technical Specifications | Specification | Value | |---------------|-------| | ASIN | B004H31AUK | | Brand | pentek | | Customer Reviews | 4.0 out of 5 stars 50 Reviews | | Enclosure Material | Resin | | External Testing Certification | FDA | | Global Trade Identification Number | 00051678321034 | | Item Dimensions D x W x H | 11.4D x 11.4W x 50.8H Centimeters | | Item Type Name | Big Blue Water Softener Cartridge, 20" x 4.5 | | Item Weight | 4.4 kg | | Manufacturer | Pentair Industries | | Manufacturer Part Number | 155321-43 | | Material | Resin | | Model number | WS-20BB | | Number of Items | 1 | | Product Benefits | Reduces hardness, minerals, and scale deposits in low flow rate applications; Protects sensitive water delivery equipment; Provides superior protection for medical equipment, coffee and espresso appliances, beverage and food service machines Product Benefits Reduces hardness, minerals, and scale deposits in low flow rate applications; Protects sensitive water delivery equipment; Provides superior protection for medical equipment, coffee and espresso appliances, beverage and food service machines See more | | Product Dimensions | 11.4D x 11.4W x 50.8H Centimeters | | UPC | 051678321034 | | Unit Count | 1.0 Count | ## Product Details - **External Testing Certification:** FDA - **Item Weight:** 9.7 pounds - **Material:** Cation Resin - **Product Dimensions:** 4.5"D x 4.5"W x 20"H ## Images ![Pentair Pentek WS-20BB, 20" Big Blue Water Softener Cartridge, 20" x 4.5" | Sodium-Form Cation Resin Reduces Hard Water Scale in Pipes and Appliances, 4,500-Grain Capacity - Image 1](https://m.media-amazon.com/images/I/41szp0fveqL.jpg) ![Pentair Pentek WS-20BB, 20" Big Blue Water Softener Cartridge, 20" x 4.5" | Sodium-Form Cation Resin Reduces Hard Water Scale in Pipes and Appliances, 4,500-Grain Capacity - Image 2](https://m.media-amazon.com/images/I/71ZZBSPbwML.jpg) ## Customer Reviews ### ⭐⭐⭐⭐⭐ They really work *by D***H on 5 June 2016* I was skeptical about this filter. I feared that (1) it wouldn't filter well, or it would have a reduced flow rate compared to the activated carbon filter that we were using. And (2) I feared that the "water softening" claim would be a gimmick of some sort. However, I am very pleased that this filter performs as claimed. The flow rate is slightly higher than the pleated/carbon filters that we replaced. The filtering is fine, with no noticeable increase in solids. And the filtered water is actually soft. We can lather in the shower; the dishwasher actually works now; the clothes washing machine produces better results. I will buy these again -- this is now our preferred filter. We live in northeast Wyoming right next to a creek. Our well is only 20 feet deep, and we are basically drinking creek-water. So, we depend on the big blue filter and a UV-lamp system to make our water potable. With activated carbon filters and the UV system, we were safe. But the water was very hard. We don't have room for a traditional water softening system without major remodeling. So, this filter provides a convenient upgrade. Yes, the filters are expensive, but in my opinion, they are a good value. ### ⭐⭐⭐⭐ Four Stars *by B***R on 30 April 2018* Great price, remove most but not all mineral from water. ### ⭐ Poor quality *by R***D on 11 February 2024* I used this brand softener filter cartridge to replace the EMI brand filter cartridge that did the same thing with out any trouble for over 6 months but this Pentair filter started substantially reducing water flow with in 30 days of use. When I removed it from the housing, I noticed the cartridge had been collapsing. ## Frequently Bought Together - Pentair Pentek WS-20BB, 20" Big Blue Water Softener Cartridge, 20" x 4.5" - Pentair Pentek EPM-10 Carbon Water Filter, 10-Inch, Under Sink Modified Epsilon Carbon Block Replacement Cartridge with Bonded Powdered Activated Carbon (PAC) Filter, 10" x 2.5", 10 Micron - Pentair Pentek CBC-20BB Big Blue Carbon Water Filter, 20-Inch, Whole House Carbon Block Replacement Cartridge with Bonded Powdered Activated Carbon (PAC) Filter, 20" x 4.5", 0.5 Micron --- ## Why Shop on Desertcart? - πŸ›’ **Trusted by 1.3+ Million Shoppers** β€” Serving international shoppers since 2016 - 🌍 **Shop Globally** β€” Access 737+ million products across 21 categories - πŸ’° **No Hidden Fees** β€” All customs, duties, and taxes included in the price - πŸ”„ **15-Day Free Returns** β€” Hassle-free returns (30 days for PRO members) - πŸ”’ **Secure Payments** β€” Trusted payment options with buyer protection - ⭐ **TrustPilot Rated 4.5/5** β€” Based on 8,000+ happy customer reviews **Shop now:** [https://www.desertcart.tn/products/439736822-pentair-pentek-ws-20bb-20-big-blue-water-softener-cartridge](https://www.desertcart.tn/products/439736822-pentair-pentek-ws-20bb-20-big-blue-water-softener-cartridge) --- *Product available on Desertcart Tunisia* *Store origin: TN* *Last updated: 2026-11-12*