Skip to content
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.

Cryptosporidium and Giardia are chlorine-resistant protozoan cysts, so disinfection alone does not always stop them. We only rank filters certified to NSF/ANSI 53 for cyst reduction (a roughly 1-micron absolute mechanical claim) or to NSF/ANSI 58 for reverse osmosis, verifiable on an official database. A filter that only claims 'cyst reduction' without that certification does not appear here.

How we score: We require a verifiable NSF/ANSI 53 (or 58) cyst-reduction certification on an official database, then rank by composite 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 reduce: chlorine taste and odor, chloramine, lead, mercury, cysts, VOCs, MTBE, turbidity, PFOA, PFOS
    • Cartridge life: 500 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 reduce: lead, chlorine taste and odor, chloramine, PFOA, PFOS, VOCs, mercury, asbestos, cysts, MTBE, microplastics, pharmaceuticals
    • Cartridge life: 500 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 reduce: chlorine taste and odor, lead, VOCs, sediment, cysts
    • Cartridge life: 1,600 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 reduce: chlorine taste and odor, lead, VOCs, chloramine, mercury, cysts, pharmaceuticals
    • Cartridge life: 651 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 equivalent for everyday use.
Will a standard carbon pitcher remove cysts?
Not unless it carries a specific NSF/ANSI 53 cyst-reduction certification. The claim depends on an absolute pore size near 1 micron, which an ordinary carbon pitcher is not built to guarantee, so we do not credit it without the certification.

Related guides