Whole house water filter cartridge types fall into two families: sediment cartridges that catch particles, and media cartridges that adsorb or react with dissolved contaminants. Most houses need one of each, staged in that order, because the sediment cartridge is what stops the expensive media cartridge from blinding off early.
Sediment cartridges: spun, pleated and wound
Melt-blown spun cartridges are graded through their depth and are the cheap general-purpose choice. String wound cartridges load even more of their depth and suit wells producing sand or iron floc, at a nominal rather than absolute rating. Pleated cartridges present a large surface area with a sharper cut, and some polyester pleats can be rinsed and reused a few times. Where sediment is heavy, stage a coarse cartridge into a finer one instead of asking a single fine cartridge to do everything.
Carbon block against granular activated carbon
A carbon block is compressed carbon with a fine pore structure, so it filters particles as well as adsorbing chlorine, taste and odor, and many blocks carry certified claims for specific contaminants. It also drops more pressure and clogs if sediment reaches it. Granular activated carbon is loose media in a cartridge shell: less pressure drop and more flow, but water can channel through it, and its claims are usually limited to taste, odor and chlorine. On chloraminated supplies, specify catalytic carbon in either form.
Specialty cartridges for specific problems
KDF media, a copper and zinc alloy, is used with carbon to handle chlorine and inhibit bacterial growth inside the housing. Calcite or acid-neutralizing cartridges raise the pH of aggressive well water that is eating copper pipe. Iron reduction cartridges exist for light iron duty, though anything more than a trace belongs in a backwashing filter rather than a cartridge. Polyphosphate cartridges sequester hardness to inhibit scale without softening, which is a stopgap, not a substitute for a softener.
Sizing, staging and housings
Big-blue housings are the standard whole-house format because their larger cartridges hold more, drop less pressure and last longer than the slim under-sink size. Order matters: sediment first, then carbon, then any specialty stage, so that each protects the next. Fit isolation valves and pressure gauges on both sides of the bank so you can measure the drop rather than guess at it, and leave clearance below each housing for the sump to come off. Our whole house water filter guide covers picking the housing bank itself.
Questions people ask about whole house water filter cartridge types
Which cartridge type goes first in a whole house filter?
Sediment always goes first. It protects the carbon and specialty cartridges behind it, which cost more and clog quickly if grit reaches them.
Carbon block or granular carbon for a whole house filter?
Carbon block for stronger contaminant claims and finer filtration, granular carbon where flow and pressure matter more than the certification list.
Can one cartridge do sediment and carbon together?
Combination cartridges exist and suit light duty, but they exhaust at whichever function fails first. Separate stages last longer and are cheaper to maintain.