KDF 55 vs KDF 85: What’s the Difference?
KDF 55 vs KDF 85: What’s the Difference?
metals, and other water-quality concerns. KDF 55 and KDF 85 are both copper-zinc media, but each is intended for a different type of application. The right choice depends on your water source and the contaminants you want to reduce.
What Is a KDF Water Filter?
A KDF water filter treats water with a high-purity copper-zinc alloy through an oxidation-reduction, or redox, reaction. As electrons move between the media and certain substances in the water, contaminants such as free chlorine and some dissolved metals can be reduced. In suitable filtration applications, KDF media may also help control bacteria, algae, and fungi growth.
A KDF filter alone does not constitute a complete filtration system. Since different media target different contaminants, it is often used alongside activated carbon or sediment filtration.
What Is KDF 55?
KDF 55 is a copper-zinc filtration medium made up of approximately 50% copper and 50% zinc. Its main purpose is to reduce free chlorine and water-soluble heavy metals, which makes it especially suitable for municipal water applications.
In homes supplied by city water, KDF 55 can serve as a useful filtration stage when reducing chlorine or dissolved metals is a priority. It is also often paired with activated carbon for broader filtration performance.
What Is KDF 85?
KDF 85 contains a different copper-to-zinc ratio: approximately 85% copper and 15% zinc. It is mainly used to reduce iron and hydrogen sulfide, so it is particularly suited to treating groundwater and well water.
Iron may leave orange or brown stains on fixtures. Hydrogen sulfide, by contrast, is commonly linked to a rotten-egg odor. When those are the primary water problems, KDF 85 is generally the more suitable option.
KDF 55 vs KDF 85
The biggest difference is not simply the number in the name. The two media have different copper-zinc compositions and are optimized for different water-quality concerns.
Feature | KDF 55 | KDF 85 |
Copper/Zinc composition | Approx. 50% / 50% | Approx. 85% / 15% |
Primary application | Chlorine & dissolved heavy metals | Iron & hydrogen sulfide |
Typical water source | Municipal water | Well/groundwater |
Chlorine reduction | Strong | Not the primary application |
Iron reduction | Not the primary application | Strong |
Hydrogen sulfide reduction | Not the primary application | Strong |
Bacteria & scale control | Yes | Yes |
Research comparing the two media similarly identifies KDF 55 as better suited to chlorine and heavy-metal reduction, while KDF 85 is better suited to iron and hydrogen sulfide.
Which KDF Filter Is Better for City Water?
If your home gets treated municipal water and your main concerns are chlorine, its taste, and certain dissolved metals, KDF 55 will generally be the better choice.
Many municipal-water filtration systems use KDF 55 alongside activated carbon. KDF media targets chlorine and certain dissolved metals; activated carbon adds further reduction of taste, odor, and many organic compounds.
Which KDF Filter Is Better for Well Water?
For well water, the right choice depends on the results of the water analysis. When iron, manganese, or hydrogen sulfide are the main concerns, KDF 85 is generally the better-suited KDF media.
However, well water may contain several contaminants simultaneously, so the test results determine whether treatment needs to include sediment filtration, carbon, KDF, iron-specific media, softening, or other technologies.
KDF Filter vs Activated Carbon
KDF and activated carbon work differently and can complement each other.
Activated carbon is widely used to improve taste and odor and reduce chlorine and many organic contaminants. KDF uses a redox reaction and is particularly useful for chlorine and certain dissolved metals, while KDF 85 has a more specialized role in iron and hydrogen sulfide reduction.
For this reason, combining KDF with activated carbon can provide broader filtration than relying on either medium alone.
PUREPLUS KDF + Activated Carbon Filtration
PUREPLUS also combines KDFÂ 55Â with premium coconut shell activated carbon in selected whole-house filter cartridges. This combination is designed to provide broader filtration than KDF alone.
Activated carbon reduces chlorine, unpleasant tastes, odors, and common impurities. KDF media adds treatment for certain dissolved metals, making this composite cartridge a practical choice for homeowners who want several filtration functions in one replacement cartridge.
BUY PUREPLUS KDF WHOLE HOUSE WATER FILTER
Conclusion
The best choice depends on your water source and actual water-quality concerns. For broader household filtration, combining KDF with activated carbon and sediment filtration can provide a more complete approach to water treatment.
If you’re not sure which PUREPLUS filter is right for your water, contact the PUREPLUS customer service team for personalized recommendations based on your water quality and filtration needs.
