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FilterScored

Water · Best-of

Best Water Filter for Cysts (Cryptosporidium and Giardia)

Bottom line

In our scoring the best water filter for cysts is one certified to NSF/ANSI 53 for cyst reduction with a low cost per gallon. Among our scored units the Culligan US-EZ-4 leads, with the Aquasana AQ-5200 close behind.

If you're filtering for cysts, the thing to understand is that Cryptosporidium and Giardia are chlorine-resistant - so the disinfection your utility does won't always stop them, and that's the gap a filter fills. We rank only filters certified to NSF/ANSI 53 for cyst reduction (a mechanical claim that hinges on a roughly 1-micron pore size) or to NSF/ANSI 58 for reverse osmosis, verifiable on an official database. A filter that just claims 'cyst reduction' without that certification doesn't appear here.

How we score: A filter needs a verifiable NSF/ANSI 53 (or 58) cyst-reduction certification on an official database to qualify - then we rank what's left by overall score.

  1. 17.5
    Culligan US-EZ-4 Under-Sink

    The Culligan US-EZ-4 Under-Sink is a under sink water filter. It is third-party certified (IAPMO) to reduce chlorine taste and odor, chloramine, lead, mercury, cysts, VOCs, MTBE, turbidity, PFOA, PFOS. It is also marketed for pharmaceuticals, for which we found no accredited third-party certification (so we award no certification credit; this is not a finding that it fails to reduce them). Running cost works out to about $0.091 per gallon.

    • Certified to reducechlorine taste and odor, chloramine, lead, mercury, cysts, VOCs, MTBE, turbidity, PFOA, PFOS
    • Cartridge life500 gallons
    • Cost per gallon$0.091
  2. 27.2
    Aquasana AQ-5200 Under-Sink

    The Aquasana AQ-5200 Under-Sink is a under sink water filter. It is third-party certified (WQA) to reduce lead, chlorine taste and odor, chloramine, PFOA, PFOS, VOCs, mercury, asbestos, cysts, MTBE, microplastics, pharmaceuticals. Running cost works out to about $0.148 per gallon.

    • Certified to reducelead, chlorine taste and odor, chloramine, PFOA, PFOS, VOCs, mercury, asbestos, cysts, MTBE, microplastics, pharmaceuticals
    • Cartridge life500 gallons
    • Cost per gallon$0.148
  3. 36.8
    Frizzlife SK99 Under-Sink Filter

    The Frizzlife SK99 Under-Sink Filter is a under sink water filter. It is third-party certified (IAPMO) to reduce chlorine taste and odor, lead, VOCs, sediment, cysts. It is also marketed for chloramine, mercury, cadmium, fluoride, PFOA, PFOS, for which we found no accredited third-party certification (so we award no certification credit; this is not a finding that it fails to reduce them). Running cost works out to about $0.031 per gallon.

    • Certified to reducechlorine taste and odor, lead, VOCs, sediment, cysts
    • Cartridge life1,600 gallons
    • Cost per gallon$0.031
  4. 44.1
    Epic Smart Shield Under-Sink

    The Epic Smart Shield Under-Sink is a under sink water filter. It is third-party certified (IAPMO) to reduce chlorine taste and odor, lead, VOCs, chloramine, mercury, cysts, pharmaceuticals. It is also marketed for PFAS, PFOA, PFOS, microplastics, for which we found no accredited third-party certification (so we award no certification credit; this is not a finding that it fails to reduce them). Running cost works out to about $0.177 per gallon.

    • Certified to reducechlorine taste and odor, lead, VOCs, chloramine, mercury, cysts, pharmaceuticals
    • Cartridge life651 gallons
    • Cost per gallon$0.177

FAQ

Does boiling kill Cryptosporidium and Giardia?
Yes - bringing water to a rolling boil for one minute inactivates these cysts, which is why utilities issue boil-water notices. A filter certified to NSF/ANSI 53 for cyst reduction is the at-the-tap version of that for everyday use, so you're not boiling water all day.
Will a standard carbon pitcher remove cysts?
Not unless it carries a specific NSF/ANSI 53 cyst-reduction certification, so don't assume yours does. The claim hinges on a pore size near 1 micron, which an ordinary carbon pitcher isn't built to guarantee - which is why we won't credit one without the certification.

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