Filters for 20" Big Blue Housings (20" x 4.5")
Pentek - GAC-20BB - 20" x 4.5" Granular Activated Carbon Filter
Pentek - CBC-20BB - 20" x 4.5" Big Blue Carbon Block Filter 0.5 Micron
Empty Refillable Cartridge 20" x 4.5" Clear
Replacement cartridges for 20" Big Blue whole-house filter housings. Every filter on this page is the 20" x 4.5" size (sometimes listed as 4.5" x 20" or 20" BB), the standard fit for Pentek Big Blue, Watts, PureT and most other 20" whole-house housings.
Not sure which type you need?
- Sediment (spun, pleated, string wound, melt blown): removes sand, rust and silt. Use 20–50 micron as a first stage on well water, 5 micron for general use, 1 micron before carbon or UV.
- Carbon block (CTO): reduces chlorine taste and odor for city water. Choose a chloramine-rated block if your utility uses chloramine.
- Specialty: KDF/GAC for heavy metals and hydrogen sulfide, iron reduction, softening resin, mixed-bed DI, and arsenic cartridges.
Most whole-house cartridges are changed every 3–6 months, or sooner if water pressure drops. Questions about fit? Call (714) 541-6600.
Stage-by-stage fit guides: Generic / builder-grade 2-Stage 20" Big Blue · Generic / builder-grade 3-Stage 20" Big Blue · Pentek / Pentair Big Blue 20" · iSpring WGB22B · iSpring WGB32B · iSpring WGB32BM · Home Master HMF2SDGC · Home Master HMF2SMGCC · Home Master HMF3SDGFEC · Express Water WH300SCKS · APEC CB3-SED-CAB-CBC20-BB · APEC CB3-SED-KDF-CAB20-BB · APEC CB3-SED-IRON-CAB20-BB · Kind Water E-1000 · Kind Water E-3000 · Aquaboon 2-Stage 20" Big Blue · Aquaboon 3-Stage 20" Big Blue · Bluonics 3-Stage 20" Big Blue · Geekpure 3-Stage 20" Big Blue · Membrane Solutions 3-Stage 20" Big Blue · Brio Whole House 20" Big Blue · Tier1 20" Big Blue Kit · Waterdrop 2-Stage 20" Big Blue · SimPure DB20P-3 · AFWFilters / Oceanic 3-Stage 20" Big Blue Well Iron · Crystal Quest Big Blue Iron/Mn/Sulfide Cartridge. See all 154 systems.
