Filters certified for cysts — 1,104 models, and twelve you can carry

By Andrew Bates, FounderPublished 2026-09-10Updated 2026-09-10

The widest certified population here — 1,104 distinct models from 88 companies held an NSF/ANSI 53 cyst reduction claim on 2026-09-10. But it concentrates in fitted and refrigerator formats: 611 plumbed-in, 311 refrigerator filters, and just twelve pitchers, gravity systems and faucet mounts combined.

The widest certified population on this site

Cyst reduction has more products behind it than any other health claim covered here. NSF’s listing on 2026-09-10:

	Cyst reduction, NSF/ANSI 53
Rows NSF returned	1,746
Distinct model designations	1,104
Companies	88

For scale, the lead claim is held by 615 distinct models and total PFAS by 49.

→ Which claims exist at all, and how populated each is

So the question is not whether a certified option exists. It is whether one exists in the format you need — and that is where this claim behaves unlike any other.

It is not portable

Category	Models
Plumbed-in	493
Refrigerator filter, aftermarket	216
Commercial modular	160
Plumbed-in to separate tap	118
Refrigerator filter, integrated	95
Counter-top connected to sink faucet	9
Pour-through gravity system	7
Pour-through (pitcher)	4
Faucet mount	1
Point-of-entry (whole-house)	0

Twelve models across pitchers, gravity systems and faucet mounts. Out of 1,104.

Set that against microplastics, where 64 pitchers hold the claim, or lead, where 29 faucet mounts do. Cyst reduction concentrates almost entirely in fitted systems and refrigerator cartridges.

→ Microplastics, where the format spread is the opposite

And the formats that are missing are the portable ones — the pitcher you would buy in a hurry, the faucet mount for a rental, the jug you would take away. Those are exactly the situations where someone reaches for a cyst filter.

Why the claim sits where it does

Because a cyst claim is a barrier claim, not a chemistry one.

EPA gives Cryptosporidium parvum at 4 to 6 microns and Giardia lamblia at 8 to 12. EPA and CDC name filters using reverse osmosis, those labelled absolute one micron, or those certified to NSF/ANSI 53 for cyst removal as providing assurance of removing Cryptosporidium.

An absolute pore rating at that size needs a dense medium and pressure behind it. Gravity-fed pitchers are working against both, which is a plausible reason the certified population looks the way it does — though NSF’s listing records the distribution, not the cause.

→ Cryptosporidium and Giardia, and why EPA requires removal → Micron ratings, absolute and nominal

The decision framework

1. Check what you already own before buying anything

Refrigerator filters are 311 of the 1,104, and plumbed-in formats another 611. Between them that is 922 of the 1,104 certified models, and both are things households commonly already have.

If you have a fridge dispenser or an under-sink filter, look the cartridge model up first. This is the claim you are most likely to hold already without knowing it.

→ How to read an NSF listing, footnotes included

2. Decide whether you need it portable

If a fitted system works, you have 611 plumbed-in options and the decision is ordinary.

If you need a pitcher or a faucet mount, the certified field is twelve models. That is not a reason to give up — it is a reason to search the listing by claim rather than browsing a shelf.

3. Do not treat it as a whole-house problem

No point-of-entry product held a cyst claim in this listing, which matches the wider census across twelve claims.

→ What a whole-house filter is certified to do

4. Separate this from emergency response

A boil water notice is not a filter problem. The instructions your utility and health department issue are specific to the event, and this page does not substitute for them.

Applying the framework: who holds the claim

Company	Models
Everpure LLC	212
Qingdao Ecopure Filter Co., Ltd.	209
Solventum Purification Inc.	118
Hydronovation Inc.	62
Microfilter Co., Ltd.	52
Pentair Residential Filtration	34
Paragon Water Systems	28
Antunes	25
Water Channel Partners	20
Doulton Water Filters	19

The remaining 78 companies hold fewer than 19 models each.

Notes tied back to the criteria

Everpure and Qingdao Ecopure are 421 of the 1,104 between them, and they sit at opposite ends: Everpure’s listing is heavily commercial modular, Qingdao Ecopure’s is aftermarket refrigerator filters. Neither is where a household browsing a shop would start.
Qingdao Ecopure held 175 of the lead-certified aftermarket fridge filters in the separate lead roster, so the same company dominates both fridge-filter populations. Aftermarket cartridges are listed as many part numbers covering different fitments, which inflates model counts relative to distinct products.
Doulton and Paragon are point-of-use specialists, consistent with the concentration in fitted formats.
Nothing here distinguishes models on performance. NSF records claim membership, not a removal percentage.

The decision path

Your situation	What decides it	Where that lands you
Have a fridge dispenser	311 fridge models hold it	Look up your cartridge first
Have an under-sink filter	611 fitted models hold it	Look up the model first
Want a pitcher	Four hold the claim	Search by claim, not by shelf
Want a faucet mount	One holds the claim	Search by claim, or change format
Want whole-house coverage	No certified example	Point-of-use instead
Under a boil water notice	Not a filter decision	Follow the issued instructions
Comparing on micron rating	Absolute, not nominal	An absolute one micron rating

Choose a plumbed-in or under-sink system if

You want the widest choice, at 493 plumbed-in and 118 to a separate tap.
The water you care about is the water you drink at home.

Choose a refrigerator filter if

You already have a dispenser. 311 models hold the claim, and confirming costs nothing.

Choose a pitcher or gravity system if

You need it portable and are prepared to search the listing for one of the eleven certified pour-through and gravity models rather than browsing.

Choose to buy nothing if

Your supply is a filtered surface water system meeting its treatment requirements, nobody in the household is immunocompromised, and you have no other reason to filter.

→ Cryptosporidium and Giardia: what your utility already does

Mistakes that cost the most money

Buying a pitcher for cysts without checking. Four pour-through models hold the claim out of 1,104. The category is not the claim.

Replacing a fridge cartridge with an uncertified equivalent. The original may hold a cyst claim and the aftermarket replacement may not. Both are listed separately.

Buying whole-house for it. No point-of-entry product holds the claim here, and cysts are an ingestion concern.

Reading a nominal micron rating as sufficient. Nominal describes an average pore. EPA and CDC name the absolute rating for Cryptosporidium specifically.

Assuming certification to NSF/ANSI 53 includes cysts. Claims vary by product and are listed per model.

Relying on a filter during a boil water notice. The issued instructions are specific to the event and take precedence.

Three situations, and what changes

You already run an under-sink or fridge filter. The most common case, and the one where the answer is probably yes already. 922 of the 1,104 certified models sit in those two formats. Look the model up before spending anything.

You rent, and cannot fit anything. One faucet mount and four pitchers hold the claim, so the search is narrow and has to be done in the listing rather than in a shop.

A household member is immunocompromised. The decision belongs with a doctor and with the statement EPA requires in your annual report, not with a filter specification. Equipment follows that conversation.

→ The Cryptosporidium statement your report must carry

The objections worth answering

“1,104 models — this must be easy.” It is, in two formats. In the formats people actually browse for on short notice, twelve models hold the claim.

“My pitcher says it filters bacteria and parasites.” Then ask which accredited body certified that claim and look it up. Four pour-through models held the NSF cyst claim on the capture date.

“Cysts are a well water problem.” Surface water systems treat for them under a federal requirement, and EPA requires every Consumer Confidence Report to carry a Cryptosporidium statement for vulnerable populations. It is a municipal topic as much as a well one.

“These figures will move.” They will. NSF dates its listings and asks readers to confirm status at source, which is why the capture date sits beside every figure here.

Who this is for

Anyone choosing a filter with cysts in mind, and particularly anyone who assumed a pitcher would cover it.

It names no recommended product and is not emergency guidance.

What to settle first

What format do I need, and does a model in that format hold the claim?

In fitted and refrigerator formats the answer is usually yes. In portable formats it is twelve models out of 1,104, and worth checking before you buy rather than after.

→ Cryptosporidium and Giardia, and why EPA requires removal → How to read an NSF listing, footnotes included → Which claims exist at all, and how populated each is

The bottom line

Cyst reduction is widely certified and barely portable. 1,104 models hold it, but 611 are plumbed-in and 311 are refrigerator filters, against twelve pitchers, gravity systems and faucet mounts combined. So the practical question is not whether a certified option exists — it is whether one exists in the format you need. If you already have a fridge dispenser or an under-sink system, check the model first, because you may be covered already. And no whole-house product holds the claim at all.

Who this is not for

This is NSF's listing on 2026-09-10 and says which models hold the claim, not how well any performs it. It is not emergency guidance: under a boil water notice, follow the instructions your utility and health department issue, which are specific to the event and override any filter. WQA and IAPMO certify to the same standards and publish separately, so a format showing few models here may hold more elsewhere.

Questions

Which filters are certified to remove Cryptosporidium?

NSF listings returned 1,746 rows for cyst reduction under NSF/ANSI 53 on 2026-09-10, resolving to 1,104 distinct models from 88 companies. EPA and CDC also name reverse osmosis and filters labelled absolute one micron as providing assurance of removing Cryptosporidium.

Do water pitchers remove Cryptosporidium?

Very few are certified to. Four pour-through models and seven pour-through gravity systems held a cyst reduction claim on 2026-09-10, out of 1,104 certified models in total. The category is almost entirely absent from this claim.

Do refrigerator filters remove cysts?

Many are certified for it. Refrigerator filters account for 311 of the 1,104 models holding a cyst claim — 216 aftermarket and 95 integrated — so a household with a fridge dispenser may already be covered by the cartridge fitted.

Is there a whole-house filter certified for cysts?

None appeared in this listing. The cyst reduction search returned 1,746 rows with no point-of-entry product among them, consistent with a wider census that found no point-of-entry product holding any health-related claim except VOC reduction.

What micron rating removes Cryptosporidium?

EPA and CDC recommend an absolute one micron filter, or one labelled for cyst removal. EPA gives Cryptosporidium parvum as 4 to 6 microns and Giardia lamblia as 8 to 12, so a one micron absolute pore sits below both with margin.

Does my city water already handle cysts?

Surface water systems must meet a 99 percent removal requirement for Cryptosporidium and 99.9 percent removal or inactivation for Giardia. That is a treatment technique rather than a measured limit at your tap, and EPA sets the health goal for both at zero.

Why do so few pitchers carry a cyst claim?

NSF records the distribution rather than the cause, but the claim is a physical barrier claim: EPA and CDC name an absolute one micron rating for Cryptosporidium, and a pore that fine needs pressure behind it. Four pour-through models held the claim on 2026-09-10.

Is cyst reduction the same as a general filtration claim?

No. Cyst reduction is a specific claim listed per model under NSF/ANSI 53, and claims vary by product. A filter certified to that standard holds a cyst claim only if the claim appears in its listing entry.

Sources — 14 claims

NSF Official Listings — Drinking Water Treatment Units, NSF/ANSI 53 cyst reduction claim search (listings current as of Thursday, September 10, 2026, 12:15 a.m. Eastern Time)
NSF listings returned 1,746 rows for cyst reduction under NSF/ANSI 53 on 2026-09-10, resolving to 1,104 distinct model designations from 88 companies, the widest certified population of any health claim searched on this site. (captured 2026-09-10)
Limits: NSF lists some models on several rows, so row counts and distinct-model counts measure different things and both are reported. Widest among the claims searched here, which is not every claim NSF offers.
NSF Official Listings — Drinking Water Treatment Units, NSF/ANSI 53 cyst reduction claim search (listings current as of Thursday, September 10, 2026, 12:15 a.m. Eastern Time)
Models holding an NSF/ANSI 53 cyst reduction claim on 2026-09-10 were concentrated in fitted and refrigerator formats — plumbed-in 493, aftermarket refrigerator filter 216, commercial modular 160, plumbed-in to separate tap 118, integrated refrigerator filter 95 — with only 4 pour-through, 7 pour-through gravity systems, 9 counter-top and 1 faucet mount, and no point-of-entry product. (captured 2026-09-10)
Limits: Category labels are NSF own, normalised for spelling variants. Counts are distinct model designations after stripping footnote markers, so they differ from the row count. One row carried no category and is excluded from these figures.
NSF — NSF/ANSI 42, 53 and 401: Filtration Systems Standards (page dated 2025-12-16)
NSF/ANSI 53 offers over 50 contaminant reduction claims, including lead, Cryptosporidium, VOCs and chromium. (captured 2026-09-09)
NSF — NSF/ANSI 42, 53 and 401: Filtration Systems Standards (page dated 2025-12-16)
Under NSF/ANSI 42 and NSF/ANSI 53, certification claims vary by product; certification to the standard does not mean a product carries every claim available under it. (captured 2026-09-09)
Limits: NSF does not print 'claims vary by product' under NSF/ANSI 401. See certification-nsf-0008 for the 401 position, which rests on weaker source language.
NSF — NSF/ANSI 58: Reverse Osmosis Drinking Water Treatment Systems (page dated 2025-12-18)
Under NSF/ANSI 58, TDS reduction is the only required claim. Every other claim, including arsenic, nitrate/nitrite, lead and cyst reduction, is optional. (captured 2026-09-10)
Limits: This is the sharpest form of "claims vary by product": a system certified to NSF/ANSI 58 is verified for TDS reduction and nothing else unless the individual claim is listed for that model.
NSF Official Listings — Drinking Water Treatment Units (listings current as of Thursday, September 10, 2026, 12:15 a.m. Eastern Time)
NSF Official Listings mark some entries "Conforms to the material requirements only", meaning the product appears under a standard without any contaminant reduction performance claim having been certified. (captured 2026-09-10)
Limits: The footnote states what was evaluated, not what the product does. It does not say the product performs badly, only that performance was not the basis of this listing. A separate listing for the same model can carry performance claims.
EPA Office of Water — Home Water Treatment Facts / Filtration Facts (published November 2005)
EPA states that filters using reverse osmosis, those labeled absolute one micron, or those certified by an ANSI-accredited organization to ANSI/NSF Standard 53 for Cyst Removal provide the greatest assurance of removing Cryptosporidium. (captured 2026-09-10)
Limits: Names the specific claim ("Cyst Removal") rather than the standard number alone, which is the distinction that matters when reading a certification.
NSF Official Listings — Drinking Water Treatment Units, reduction-claim searches filtered to the Point-of-Entry category (listings current as of Thursday, September 10, 2026, 12:15 a.m. Eastern Time)
Ten NSF reduction-claim searches returned no point-of-entry product at all on 2026-09-10: chloramine reduction under NSF/ANSI 42; lead, cyst, turbidity, total PFAS, PFOA, PFOS and chlorine reduction under NSF/ANSI 53; and fluoride and lead reduction under NSF/ANSI 58. (captured 2026-09-10)
Limits: Absences in one certifier’s listing on one date, for the claims named. They do not establish that whole-house treatment for these contaminants is impossible, and another accredited body may list such products.
EPA Office of Water — Home Water Treatment Facts / Filtration Facts (published November 2005)
EPA and CDC recommend an absolute one micron filter, or one labeled for cyst removal, to remove Cryptosporidium. (captured 2026-09-10)
Limits: This addresses Cryptosporidium specifically. A one micron absolute filter is not a general-purpose treatment and does nothing for dissolved contaminants such as nitrate or arsenic.
EPA Office of Water — Home Water Treatment Facts / Filtration Facts (published November 2005)
EPA maps contaminants to home treatment technologies: Giardia and Cryptosporidium to distillation, reverse osmosis, absolute one micron filters, ultraviolet light and cyst-certified filters; bacteria and viruses to distillation, reverse osmosis, ultraviolet light and disinfection; arsenic to adsorptive media; lead to distillation, reverse osmosis and some carbon filters; nitrates to distillation, reverse osmosis or ion exchange; and radon to activated carbon and aeration. (captured 2026-09-10)
Limits: Technology classes, not product endorsements, from a 2005 EPA sheet. "Some carbon filters" for lead is EPA’s own hedge and should be read as requiring a certified lead claim on the specific model.
EPA Office of Water — Home Water Treatment Facts / Filtration Facts (published November 2005)
EPA states that an activated carbon filter by itself is not designed to remove all disease-causing organisms, and that carbon filters have a specified shelf life and should be replaced regularly per the manufacturer instructions. (captured 2026-09-10)
Limits: Concerns activated carbon as a class. Some carbon blocks carry certified cyst reduction claims, which is a model-specific capability rather than a property of carbon.
EPA Office of Water — Home Water Treatment Facts / Filtration Facts (published November 2005)
EPA gives organism sizes in microns as Giardia lamblia 8 to 12, Cryptosporidium parvum 4 to 6, bacteria such as E. coli and salmonella 0.2 to 4, and viruses 0.004 to 0.1. (captured 2026-09-10)
Limits: Sizes explain why a micron rating works for cysts and not for viruses. EPA adds that generally only ultrafilters and reverse osmosis have holes small enough to assure virus removal, and that viruses can be killed with a disinfectant instead.
EPA — National Primary Drinking Water Regulations
EPA sets the Maximum Contaminant Level Goal for Cryptosporidium and for Giardia lamblia at zero, and regulates both by Treatment Technique. (captured 2026-09-10)
Limits: A Treatment Technique judges whether a required process was carried out, so a water report may show no concentration figure for either organism to compare against a limit.
EPA — Comprehensive Surface Water Treatment Rules Quick Reference Guide: Systems Using Conventional or Direct Filtration, EPA 816-F-10-074
EPA sets the regulated pathogen requirements as 99.99 percent (4-log) removal or inactivation of viruses, 99.9 percent (3-log) removal or inactivation of Giardia lamblia, and 99 percent (2-log) removal of Cryptosporidium. (captured 2026-09-10)
Limits: EPA states the requirement for Cryptosporidium as removal, where viruses and Giardia are stated as removal or inactivation. A 2-log requirement is a 99 percent floor, so the standard itself contemplates a fraction passing treatment.