Which Water Filter Brands Have NSF/ANSI 42 Certification?

NSF/ANSI 42 covers aesthetic effects, most commonly chlorine taste and odor, with optional claims for chloramine, particulates, iron, manganese, zinc, or aesthetic-level TDS reduction. It does not cover health-related contaminants such as lead or PFAS, which fall under separate standards instead. Brita, PUR, Waterdrop, Multi-Pure, and Culligan currently list specific models as actively certified to NSF/ANSI 42, with Culligan's certification running through WQA's Gold Seal program rather than NSF International's own directory.

A certification applies to an exact model and a named claim, and "certified" carries more verified proof than "tested to" or a manufacturer's own statement. Check the certifying body's current listing before buying. This guide breaks down the standard itself, the brands that carry it, and where Viomi's stated claims fit into that picture.

What NSF/ANSI 42 Actually Certifies (And What It Doesn't)

NSF/ANSI 42 is titled "Drinking Water Treatment Units, Aesthetic Effects." The name is the whole story: it evaluates whether a filter improves how water looks, tastes, and smells, not whether it removes something that could make you sick.

The most common claim under this standard is chlorine taste and odor reduction, one of the most common jobs activated-carbon filters are built to do. Beyond that baseline, manufacturers can submit a product for additional optional claims covered by the same standard:

• Chloramine reduction
• Particulate reduction, rated in six size classes from Class I (0.5 to under 1 micron) up to Class VI (50 microns and larger)
• Reduction of iron, manganese, or zinc
• Aesthetic-level total dissolved solids (TDS) reduction

A product doesn't need every optional claim to carry the certification, and not every NSF/ANSI 42 listing includes a chlorine taste and odor claim specifically. It only needs to be listed for the specific ones printed on its certificate.

This is a genuinely different job from NSF/ANSI 53, the standard that covers health-related contaminants like lead, volatile organic compounds, mercury, and microbial cysts. A filter can hold 42 without holding 53, and plenty of budget pitchers and faucet filters do exactly that.

The two standards are frequently certified together on the same product, and that's where the confusion starts. A box that says "NSF Certified" in large print with "42" in small print next to it is a completely different product than one that also lists 53 with a named contaminant like lead.

"Certified," "Tested To," and "Manufacturer States" Aren't the Same Claim

Three different phrases show up on filter product pages, and they carry three different levels of proof:

• Certified by NSF, WQA, or IAPMO R&T to NSF/ANSI 42 means an accredited third-party body independently verified the exact model and lists it in a public, searchable directory.
• Tested to NSF/ANSI 42 or tested with reference to NSF/ANSI 42 means a laboratory, often a firm like SGS, ran the product through the standard's test methods and produced a report. That's real evidence, but it isn't the same as an active certification listing for that model.
• The manufacturer states a product meets NSF/ANSI 42 performance is the company's own claim, worth taking seriously if it names a specific report, but not verified against a public directory on its own.

None of these are automatically dishonest, and a solid lab report from a reputable firm is genuine evidence of performance. But if a specific certification is the deciding factor in a purchase, the way to confirm it is to search the exact model number in the certifying body's own directory rather than take the product page's wording at face value, no matter which brand is on the box.

Water Filter Brands With Active NSF/ANSI 42 Certification

The brands below currently show specific models listed as actively certified to NSF/ANSI 42 in NSF International's Certified Product Listings. For Culligan, that's based on the WQA Gold Seal program instead. Culligan's own product pages state its Cullar filters and Aquasential RO system are WQA-certified to NSF/ANSI 42.

A certification covers the exact model and configuration it was issued for, not the whole brand name. Two filters that look nearly identical on a retail page can have different certified claims if one was tested for chloramine or particulates and the other wasn't. Before buying based on a specific claim, confirm the model number in front of you matches what's actually in the directory listing.

What Kind of Product Usually Carries NSF/ANSI 42

Because it's the baseline aesthetic standard, NSF/ANSI 42 shows up on nearly every category of carbon-based filter: pitchers, faucet-mount units, refrigerator and ice-maker cartridges, dedicated-faucet under-sink carbon systems, and point-of-entry whole-house carbon tanks. The common thread is a carbon media stage: granular activated carbon, a solid carbon block, or a blend with other media. Carbon is what adsorbs the chlorine and organic compounds responsible for most taste and odor complaints.

Full reverse osmosis systems also frequently carry a 42 claim, even though RO membranes themselves aren't what the standard is testing. Most RO systems include carbon pre-filter and post-filter stages that protect the membrane from chlorine and polish the water's taste afterward, and those carbon stages are what earn the 42 claim. The RO membrane itself is what gets evaluated separately under 53 and 58. Put those pieces together on one finished system, and a 42 claim ends up sitting alongside 53 and 58 as a stacked set of certifications rather than standing alone.

Viomi's own filter cartridges show the physical side of that same idea: multiple treatment stages built into a single cartridge instead of separate units. The label below lists pre-activated carbon, coconut shell carbon, and bamboo charcoal stages built into the same cartridge that also handles remineralization.

Where Viomi Fits In

Viomi Under-Sink Carbon Filter (under $80) is built around a 0.5-micron PP cotton and carbon rod cartridge (model VM-IUO1PCW-US). That cartridge handles lead, chlorine, and taste and odor in one unit, instead of splitting those jobs across two separate filters. The replacement cartridge is rated for 12 months or 8,000 gallons on municipal water and runs around $30.

Viomi also sells a direct-connect version of the same system, priced around $40. It plumbs into the cold-water line instead of running its own dedicated faucet, but uses the same cartridge and replacement cost as the dedicated-faucet version.

Viomi's product pages state NSF/ANSI 372, 53, and 42 claims for both versions. Read those three standards for what they actually cover rather than as one bundled claim: 372 concerns the lead content of the wetted materials, 53 concerns the lead-reduction performance claim, and 42 is the chlorine-taste-and-odor piece.

Those are Viomi's own stated claims, not an independent directory listing. This article checked NSF International's public directory the same way for every brand named in this piece, and neither Undersink version turned up as an active listing under the Viomi name.

For households planning a full RO system instead of a single cartridge, Viomi states that its tankless lineup carries the same chlorine-taste-and-odor claim. Separately, SGS lab testing that Viomi cites for the line shows both the Viomi M1 ($799.99) and Viomi V8 PRO (around $400) reducing lead by more than 99.87 percent at a new filter's start of life. That's well clear of the NSF/ANSI 53 threshold for a lead-reduction claim.

The Viomi M1's official page states it is "NSF/ANSI 42 certified to reduce chlorine, bad taste, and odor," alongside its NSF/ANSI 58 and 372 claims. The Viomi V8 PRO carries a broader stack: NSF/ANSI 42, 53, and 58 performance claims, plus the 372 lead-free material requirement.

As with the Viomi Under-Sink Carbon Filter, these are the claims on Viomi's own product pages, not an independent directory listing. Neither model turned up as an active listing in NSF International's directory either.

For the fuller picture, including how that same SGS testing tracks PFAS, PFOA/PFOS, and fluoride on the Viomi M1 and Viomi V8 PRO, see Which Water Filter Brands Have NSF/ANSI 58 Certification?. Those numbers are broken out in full there.

If Chlorine Taste Isn't Your Only Concern

NSF/ANSI 42 alone tells you a filter improves taste and odor. It doesn't tell you anything about lead, PFAS, arsenic, or other health-related contaminants. Those fall under separate standards:

• NSF/ANSI 53 covers health-effect reduction claims on carbon and RO systems.
• NSF/ANSI 58 covers reverse osmosis system performance, including TDS and, on some models, PFOA/PFOS.
• NSF/ANSI/CAN 372 covers the lead content of a product's wetted materials, a materials-compliance claim rather than a lead-reduction performance claim.

If your water utility's annual report or a private well test shows something beyond chlorine taste, a 42-only filter isn't the tool for that problem, regardless of the brand on the box.

How to Verify a Specific Product's NSF/ANSI 42 Status Yourself

1. NSF International: search the Certified Product Listings at info.nsf.org by trade name, standard number (42), and exact model.
2. WQA: search the Gold Seal directory at find.wqa.org by manufacturer or brand name.
3. IAPMO R&T: search their certification listings directly on iapmort.org, since some brands certify through this body instead.

Search using the exact model number printed on the cartridge or product box, not just the brand name, since certification is issued per model and sometimes per finish or capacity variant. If chloramine or particulate reduction specifically matters to you, confirm that claim is named in the listing itself rather than assuming a general NSF/ANSI 42 certification automatically covers it.

FAQ

Does NSF/ANSI 42 certification mean the water is safe to drink? No. It confirms a filter improves taste, odor, or appearance to the standard's requirements. It doesn't evaluate lead, PFAS, cysts, or other health-related contaminants. That's the role of NSF/ANSI 53, 58, or 401 depending on the contaminant.

Is NSF/ANSI 42 certification required by law to sell a water filter in the US? No, at the federal level it's a voluntary industry certification, and a manufacturer can legally sell an uncertified filter as long as it doesn't make unsupported claims about performance. Some states add their own registration or labeling rules for water treatment devices on top of that, so requirements can vary by where a filter is sold.

What's the difference between NSF/ANSI 42 and NSF/ANSI 53? NSF/ANSI 42 covers aesthetic effects: chlorine taste and odor, chloramine, particulates, and similar non-health-related claims. NSF/ANSI 53 covers health-related contaminants like lead, mercury, VOCs, and microbial cysts. A filter can be certified to one, both, or neither, and the two are evaluated independently even when printed on the same certificate.

Can a filter be certified to NSF/ANSI 42 but not 53? Yes, and this is common on budget pitchers and basic faucet-mount filters. It means the filter has been verified to improve taste and odor but hasn't been separately verified for lead or other health-related contaminants.

Which Viomi products reference NSF/ANSI 42? Viomi's official product pages state that the Viomi Under-Sink Carbon Filter, Viomi M1 and Viomi V8 PRO carry an NSF/ANSI 42 claim for chlorine, taste, and odor reduction. The stated full claim stack differs by product: 372, 53, and 42 for the Viomi Under-Sink Carbon Filter; 42, 58, and 372 for the Viomi M1; and 42, 53, 58, and 372 for the Viomi V8 PRO. For the Viomi M1 and Viomi V8 PRO, Viomi also cites separate SGS lab testing. A search of NSF International's public directory didn't turn up active listings for any of the three under the Viomi name, so the NSF/ANSI claim stacks above are Viomi's own product-page statements, while the SGS testing is separate lab evidence rather than a directory record.

How do I check whether a specific product I'm considering is actually certified? Search the exact model number, not just the brand, in NSF International's Certified Product Listings, WQA's Gold Seal directory, or IAPMO R&T's certification listings. If a specific optional claim like chloramine or particulate reduction matters to you, confirm it's named in that listing.

Which Option Fits Your Situation

NSF/ANSI 42 is fundamentally an aesthetic-effects standard, not a health-contaminant one, so the real question isn't which brand to pick, it's how serious the rest of your water concerns are.

• Chlorine taste and odor is genuinely the whole complaint, nothing more: Brita, PUR, Waterdrop, and Multi-Pure all show up directly in NSF International's own directory for this job, and Culligan's carbon products are listed through WQA. Any of them handles a straightforward taste-and-odor complaint at the pitcher or faucet-mount level. If lead is even a mild secondary concern, Viomi Under-Sink Carbon Filter is the more direct fix: one cartridge stacking 372, 53, and 42 claims covers taste, odor, and lead together, running $66.99 for the direct-connect version or $78.99 for the dedicated-faucet version. That's one filter instead of two. That lead-reduction claim is Viomi's own product-page statement rather than an independent directory listing, the same manufacturer-stated tier described earlier. The SGS lab testing behind the Viomi M1 and Viomi V8 PRO below sits in the separate, lab-tested tier, one step closer to independent verification.
• A full RO system is already the plan, and taste and odor is just one item on a longer certification checklist: the Viomi M1 (42, 58, and 372) and Viomi V8 PRO (42, 53, 58, and 372) each fold a chlorine taste-and-odor claim into a fuller stack of standards claims. Separately, Viomi's own SGS lab testing shows over 99.87 percent lead reduction at a new filter's start of life. At that point, 42 isn't the headline anymore, it's one line among a much longer list of what the system is doing for the water.
• The concern was never really about taste, it's lead, PFAS, or arsenic showing up on a water report: don't stop at a 42 certification regardless of brand. Confirm the specific contaminant is named for the exact model, either in an active NSF, WQA, or IAPMO R&T directory listing, or in manufacturer-cited lab testing such as an SGS report. Viomi states that the Viomi M1 and Viomi V8 PRO fold PFOA/PFOS and TDS reduction into their NSF/ANSI 58 claim stack, backed by the SGS lab testing referenced above, if a full RO system covering that ground is the direction you're leaning.

The habit that matters more than any single brand name here is checking the exact model number against the certifying body's own directory. "NSF/ANSI 42 certified" and "NSF/ANSI 53 certified" answer two completely different questions, and a filter can honestly ace one without ever having attempted the other.