How We Check Claims

Water treatment is full of claims that are easy to print and hard to check. These are the rules every article on this site follows.

Claim labels

When we compare products, every contaminant claim gets one of three labels:

• Certified: the product is listed for that contaminant, under the named standard, by an accredited certifier such as NSF, WQA, IAPMO or CSA. We link the listing and note the date we checked it.
• Lab-tested only: the maker publishes a report from an independent lab, but the product is not certified for that claim. Lab reports are useful, but nobody audits how the product tested relates to the one you buy.
• Maker claim only: we found no certification listing and no independent lab report.

Certification standards differ by what they cover. NSF/ANSI 42, for example, covers taste and odor (such as chlorine), while health-related contaminants such as lead fall under other standards. We name the standard on every certified claim, and we check the listing itself, not the box, the maker’s website or another review.

Your water first

Before recommending a product, we point you to the data on your own water: your utility’s annual water quality report (the Consumer Confidence Report) or a test. We compare levels with the legal limits set by the EPA and your state, and with health-based guidelines where they differ, and we say which is which.

Health evidence

When we explain what a contaminant does to health, we cite peer-reviewed research and official assessments (PubMed, the EPA, the CDC, the WHO) and rate the main claim:

• Strong evidence: supported by multiple large studies, systematic reviews or meta-analyses.
• Moderate evidence: supported by several studies, with limitations.
• Weak evidence: small, early or inconsistent studies only.
• Insufficient evidence: no reliable human studies yet.

We describe studies concretely: who was studied, how many, at what exposure, and what was measured. A risk at high exposure doesn’t mean the same risk at the level in your tap, and we say so.

How articles are written and updated

Articles are researched and drafted with the help of AI tools, then checked by a person before publishing: every claim against its cited source and every certification label against the listing. Certifications and rules change, so we recheck our comparison pages regularly, and the date at the top of each article shows when it was last updated.

What we don’t do

We don’t run our own lab tests, and we never imply that we do. We don’t publish invented reviews, testimonials or “we tried it” stories. Experience from real people appears only with their permission, and attributed to them.

Commercial relationships

We earn money through affiliate links, advertising and introductions to installers and labs. Partners never see or approve our content before publication, and what a partner pays never changes a claim label. See our affiliate disclosure.

Corrections

Found a mistake, or a listing that has changed? Tell us. We fix factual errors promptly and note significant corrections in the article.