What our evidence labels mean
A certification record must match the exact system and the specific reduction or performance claim; a component or material claim is not complete-system certification.
Source checked: 2026-08-28 · Sources: NSF Drinking-Water Treatment Unit Registry (SRC-NSF-CERTIFICATION) · Locators: LOC-NSF-CERTIFICATION-1,LOC-NSF-CERTIFICATION-2,LOC-NSF-CERTIFICATION-3,LOC-NSF-CERTIFICATION-4,LOC-NSF-CERTIFICATION-5,LOC-NSF-CERTIFICATION-6| Label | Meaning | What it does not mean |
|---|---|---|
| Sources checked | Exact model, ASIN, manufacturer page, manual, and listing are recorded | Hands-on use or measured performance |
| Exact-system certified | A current certifier listing was matched to the exact system and claim | Every contaminant is covered |
| Component/material certified | A component or material carries a documented standard claim | The complete system is certified |
| Listing not found | We did not verify a current exact certifier record | Proof that a product fails |
Our six-step review
- Start with the water source and current evidence: municipal Consumer Confidence Report or certified-lab well test.
- Define the treatment job—sediment, aesthetic chlorine, hardness, iron/manganese, microbial risk, or another measured condition.
- Resolve exact US model, variant, ASIN, manual, replacement parts, operating limits, and retailer identity.
- Check whether certification applies to the exact system, only a component, or only a manufacturer claim.
- Compare flow, pressure, service clearance, power, drain, bypass, installation, replacement cycle, and ownership cost.
- Publish a conditional fit, reasons to pause, and checks that can end in ‘do not buy yet.’
How a product earns a place
- It represents a distinct, report-matched treatment path.
- Exact model and Amazon US identity are resolvable.
- Primary documentation exposes installation and maintenance requirements.
- Material limits can be stated plainly.
- It does not require us to convert a marketing claim into a health or safety guarantee.
What we do not claim
For PFAS, check that the exact filter's certification or performance claim names PFAS; a general water-treatment claim does not establish PFAS reduction.
Source checked: 2026-08-28 · Sources: EPA PFAS Home-Filter Guidance (SRC-EPA-PFAS) · Locators: LOC-EPA-PFAS-1,LOC-EPA-PFAS-2,LOC-EPA-PFAS-3,LOC-EPA-PFAS-4,LOC-EPA-PFAS-5We do not invent water samples, pressure readings, field installations, taste tests, laboratory results, plumber review, or years of ownership. Manufacturer reduction percentages stay attributed. A product name, media ingredient, TDS reading, or improved taste is never treated as proof that water is safe.
Freshness is split into separate checks
- Editorial review: the comparison and conclusion were materially reviewed.
- Evidence review: source documents and exact identities were checked.
- Retailer identity check: the canonical listing resolved to the requested ASIN; seller, offer, price, stock, delivery, condition, and warranty eligibility remain separate fields.
- Certification check: the exact certifier listing and claim scope were checked independently.
Sources
Editorial transparency
This page is governed by our editorial policy, review methodology, and corrections process.