Our methodology

How we decide what to tell you

Every claim on PFAS Watch is traceable to a named source. We publish the source, the date we checked it, and how confident we are — so you can judge the evidence yourself.

Where our data comes from

We rank every source into one of three tiers. Higher tiers carry more weight in a rating.

Tier 1 · Government verified

Official datasets like the EPA CompTox Dashboard and state PFAS registries. The strongest evidence we use.

Tier 2 · Peer-reviewed

Studies published in scientific journals and indexed in PubMed. Used to support and explain risk.

Tier 3 · Community verified

Independent lab tests submitted by the public and reviewed by our team. Always labelled, never the sole basis for a rating.

How we rate confidence

We show a confidence band, never a fake precise number. It reflects how much good evidence agrees.

High

Two or more Tier 1 sources agree, including recent data.

Moderate

Credible sources support this, but coverage is partial or ageing.

Low

Limited or conflicting evidence. Treat with caution.

Insufficient data

Not enough reliable data to assess yet. Help us by submitting a lab test.

The six risk statuses

Contains PFASLikely contains PFAS chemicals, with high or moderate confidence.

PFAS-FreeVerified PFAS-free by a credible source as of a stated year.

ReformulatedPreviously contained PFAS; the current version appears PFAS-free.

ConflictingSources disagree. See the full data breakdown on the record.

UnknownNot enough data to assess. You can help by submitting a lab test.

We answer to you, not to brands

PFAS Watch is 100% consumer-funded. No brand, supplier, industry group, or government pays us or influences a single data point. If you think a record is wrong, challenge it — every dispute is reviewed.

Dispute a record