Water filter · under-sink
Culligan US-EZ-4 Under-Sink
An under-sink filter genuinely IAPMO certified to NSF/ANSI 42, 53 and 401 for lead, cysts, VOCs, mercury and PFOA/PFOS.
Bottom line
In our scoring the Culligan US-EZ-4 Under-Sink earns 7.5/10, a solid pick, and it stands out on verified contaminant reduction (9.0/10). On the data, it holds IAPMO certification to reduce chlorine taste and odor, chloramine, lead. It works out to about $0.091 per gallon, a middling cost per gallon. Its weakest area in our scoring is total cost of ownership (5.0/10). Certification is not a substitute for a water test of your own supply.
Where to buy
Check the current price on AmazonAffiliate link: we may earn a commission at no extra cost to you. It never changes a score - how we handle this.
Total cost of ownership
Checked 42 days ago- Cost / gallon
- $0.091
- ~Annual filters
- $100/yr
Certifications
- NSF/ANSI 42chlorine, chloramine
- NSF/ANSI 53lead, mercury, cysts, VOCs, mtbe, turbidity, PFOA, PFOS
- NSF/ANSI 401pharmaceuticals
Filters only protect you on their swap schedule. Get an email reminder when this one is due - one note around swap time, nothing else.
Overview
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.
By the numbers
- Certified to reduce
- chlorine taste and odor, chloramine, lead, mercury, cysts, VOCs, MTBE, turbidity, PFOA, PFOS
- Marketed, no certification found
- pharmaceuticals
- Format
- under sink
- Cartridge life
- 500 gallons
- Cost per gallon
- $0.091
- Annual filter cost (~1,100 gal)
- $100/yr
- Flow rate
- 0.5 gpm
- Install
- under-sink with dedicated faucet and electronic life indicator
- Certifications
- IAPMO NSF/ANSI 42; IAPMO NSF/ANSI 53; IAPMO NSF/ANSI 401
Strengths
- + Verified Contaminant Reduction: 9.0/10
- + Certification Independence: 8.0/10
- + Capacity & Flow Fit: 8.0/10
Watch-outs
- No significant weaknesses flagged.
Who it is for
- · Homes with lead service lines or older plumbing (certified for lead)
- · Anyone targeting PFAS (certified for PFOA/PFOS)
What to know before buying
- · The replacement cartridge is the RC-EZ-4, rated for up to 500 gallons or about 6 months, with a twist-on/twist-off change and an electronic faucet life indicator.
- · It is tested and certified by IAPMO to NSF/ANSI 42 (chlorine taste/odor, chloramine, particulate) and NSF/ANSI 53 (lead, cysts, mercury, VOCs, MTBE, turbidity).
- · It is a carbon-block under-sink filter on a dedicated faucet, not an RO system, so it does not reduce TDS.
How it scored
Verified Contaminant Reduction
9.0/10 · 35%Held NSF/WQA/IAPMO certifications for the contaminants that matter. A claim is not a certification.
- +3NSF/ANSI 53 certified for lead ANSF/53 lead - Independently certified to reduce lead under NSF/ANSI 53.
- +3Certified for PFAS (NSF/ANSI 53 or 58) APFOA/PFOS certified - Independently certified to reduce PFOA/PFOS.
- +1NSF/ANSI 42 certified for chlorine ANSF/42 chlorine - Certified to reduce chlorine taste and odor.
- +2NSF/ANSI 401 emerging contaminants ANSF/401 - Certified for emerging contaminants such as pharmaceuticals.
Total Cost of Ownership
5.0/10 · 25%Computed cost per gallon vs the format-class median. The number nobody surfaces.
- +5Cost per gallon vs class median A$0.091/gal (below class median) - Computed cost per gallon scored against the format-class median.
Certification Independence
8.0/10 · 15%Certified on the official database vs self-claimed 'tested to' marketing.
- +5Certifications verifiable on official database A3 listings - Certifications are listed on the official NSF/WQA/IAPMO database, not just a logo.
- +3Per-contaminant reduction disclosed Bperformance data sheet - Publishes percent reduction per contaminant at rated capacity.
- ·Marketing exceeds certified scope Aclaims beyond certified scope - Marketing emphasizes contaminants the certifications do not cover.
Capacity & Flow Fit
8.0/10 · 15%Cartridge life and flow appropriate to the format.
- +3Cartridge life fits the format B500 gal (norm 500) - Rated cartridge life is appropriate for this filter format.
- +3Flow / storage disclosed and adequate B0.5 gpm - Flow rate or RO storage is disclosed and adequate for the format.
- +2Honestly rated filter life Bgallon rating matches typical use - Months claim matches the gallon rating at typical use.
Practical Fit
7.0/10 · 10%Install, footprint, and source-water readiness.
- +5Install type disclosed Cunder-sink with dedicated faucet and electronic life indicator - Install method and difficulty are disclosed up front.
- +2Predictable replacement schedule Chonest life rating - Replacement schedule is predictable from the honest gallon rating.
FAQ
- Is the Culligan US-EZ-4 Under-Sink NSF certified, and does it remove lead or PFAS?
- Per the public NSF/WQA/IAPMO databases it holds IAPMO certification to reduce chlorine taste and odor, chloramine, lead, mercury, and more. It is certified for lead. It is certified for PFAS (PFOA/PFOS).
- What is the US-EZ-4 certified to reduce?
- IAPMO certifies it to NSF/ANSI 42 for chlorine taste and odor, chloramine, and particulate, and to NSF/ANSI 53 for contaminants including lead, cysts, mercury, VOCs, MTBE, and turbidity.
- What is the replacement cartridge and how long does it last?
- It uses the RC-EZ-4 twist-in cartridge, rated for up to 500 gallons or roughly 6 months depending on use and water quality.
Compared head-to-head
Related guides
This score is our opinion under our published rubric, not a statement of objective fact or a lab test of this product. We score what third-party certifications prove; absence of a certification means we found no verification, not that a product fails to perform. Last reviewed 2026-06-06. Scored under water-v1.0. Prices were last checked 42 days ago; the freshness chip above the cost panel shows the current state. See the methodology for how each rule fires.