H2O Insider

KDF Filtration Explained

KDF (Kinetic Degradation Fluxion) uses copper-zinc granules to create an electrochemical reaction that removes chlorine, heavy metals, and inhibits bacteria.

KDF Filtration Explained

Removes

  • • Chlorine (95-99%)
  • • Lead and mercury
  • • Hydrogen sulfide
  • • Iron
  • • Bacteria (inhibits, not sterilizes)

Does Not Remove

  • • PFAS
  • • Nitrates
  • • Fluoride
  • • Viruses
  • • Total dissolved solids

KDF: Electrochemistry in Your Water Filter

KDF (Kinetic Degradation Fluxion) media was developed in the late 1980s as a complement to activated carbon in residential water treatment. The innovation was using the natural electrochemical potential between copper and zinc to drive chemical reactions that neutralize contaminants — no electricity required. When dissimilar metals contact water, they form a galvanic cell. Electrons move from the zinc to the copper, and that electron transfer converts chlorine (Cl2) to chloride (Cl-) and reduces heavy metal ions to their metallic form.

The secondary benefit is biological control. KDF media generates trace amounts of hydrogen peroxide and hydroxyl radicals as byproducts of the electrochemical reaction. These compounds inhibit the growth of bacteria, algae, and fungi within the filter housing. This is particularly valuable in shower filters where warm, humid conditions would otherwise promote biofilm growth on carbon-only media.

KDF Grades and Their Applications

KDF-55

Removes: Chlorine (up to 99%), lead, mercury, arsenic, bacteria inhibition
Best for: Shower filters, under-sink carbon combinations, countertop filters
Temperature: Works better at higher temperatures — effective in hot shower applications

KDF-85

Removes: Iron (ferrous, up to 95%), hydrogen sulfide (rotten egg odor), manganese
Best for: Well water pre-filters with iron or H2S; whole-house pre-treatment for iron-rich wells
Temperature: Standard temperature range; specific to iron and H2S chemistry

KDF-F (Fine Mesh)

Removes: Same as KDF-55, faster reaction rate
Best for: High-flow shower filters and countertop units where contact time is short
Temperature: Designed for short contact time applications at higher flow rates

KDF in Shower Filters: Chlorine vs Chloramine

KDF-55 is less effective on chloramine than on free chlorine. If your utility uses chloramine, check its water quality report to confirm. For chloraminated water, a vitamin C (ascorbic acid) cartridge stage provides more consistent chloramine neutralization.

KDF Works Best as Part of a Multi-Stage System

KDF is rarely used as a standalone filter and works best as a complementary stage to activated carbon. Carbon removes organic compounds; KDF handles chlorine, heavy metals, and biological control. The combination in shower filters and whole-house systems provides broader contaminant coverage than either technology alone. For lead, PFAS, or nitrate removal as a primary concern: KDF is a supplement, not a replacement for NSF 53- or NSF 58-certified systems.

Top Products Using This Technology

9.5
Reverse Osmosis
Waterdrop G3P800 Tankless RO

Waterdrop G3P800 Tankless RO

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$649+ $120/yr

  • ✓800 GPD capacity — near-instant delivery
  • ✓3:1 pure-to-waste ratio (efficient)
9.3
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Aquasana AQ-5300+ Under-Sink

Aquasana AQ-5300+ Under-Sink

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$149+ $60/yr

  • ✓Best mid-range under-sink (non-RO)
  • ✓800-gallon rated filter life (WQA listing)
8.8
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Hydroviv Under-Sink Water Filter

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$199+ $80/yr

  • ✓Custom-formulated for your ZIP code water report
  • ✓Free water nerd advice even if you don't buy
Price unavailable
8.7
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AquaTru Carafe Reverse Osmosis

AquaTru Carafe Reverse Osmosis

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$299+ $85/yr

  • ✓No plumbing required
  • ✓No installation required

Frequently Asked Questions