Independent water quality ratings
Know what's in your water before you drink it.
The data exists. It's just scattered across utility PDFs, EPA databases, and brand reports written to be skimmed past. WaterKnown collects it into one place, translates it, and scores it against health guidance, with the citation under every number.
Every number cited to its source Health guidance, not legal minimums Nothing invented, ever
How scoring works
The same yardstick, whether the brand likes it or not
A marketing label is not a lab report. Every score on this site comes from published data run through the same three steps, and no one can opt out of them or pay into them.
STEP 01
We collect the record
Utility Consumer Confidence Reports, EPA UCMR monitoring files, FDA retail surveys, state testing programs, brand-published lab reports, NSF certification listings. Every number keeps its citation.
STEP 02
We score against health guidance
Published results are compared to health-based guidance levels, which are usually far stricter than legal limits. Same benchmarks for every brand and every city, applied whether the result flatters them or not.
STEP 03
We grade disclosure
What a brand won't publish matters as much as what it will. A product with no current public report doesn't get an invented score. It gets a disclosure flag that says exactly that.
Reading a score
Scores run 0 to 100. The bands are deliberately strict: plenty of legal water does not clear 80.
Bottled water
Why there are no brand scores here
The FDA tested 197 bottled waters for PFAS and found detections in ten of them. It never published which ten. No agency does, which is why nobody can honestly score bottled brands from public data, us included.
197 tested
Domestic and imported bottled waters sampled at retail by the FDA between 2023 and 2024, across purified, artesian, spring and mineral types.
10 with PFAS
Eight domestic purified or spring waters carrying one to four compounds, two imported artesian waters carrying one or two. None above the drinking-water limits taking effect in 2029.
0 brands named
The one thing a shopper needs, and no public dataset contains it. What you can check is a filter's certification, which is public and model-specific.
Reading
Questions we get asked, answered properly
Guides built from the same EPA files and utility reports as the ratings.
PFAS in US tap water, state by state
EPA tested 10,297 systems. We processed every result: 3,539 had a detection, serving 152 million people.
PFAS by state, all 51 ranked
New Jersey 68% of systems, Mississippi 4%. Every state with its own systems, compounds and highest results.
How to read your water quality report
What each column means, why the lead figure is a 90th percentile, and three ways these reports mislead without lying.
Do water filters actually remove PFAS?
Only two certifications mean anything. Most pitchers carry neither, and the box will not tell you.
Why we exist
A label can say "pure spring water" and be legally true while the report that would prove it sits in a PDF nobody opens. The data isn't secret. It's scattered, unread, and written to be skimmed past. WaterKnown collects it, translates it, and holds it to health guidance instead of legal minimums. We don't run lab panels of our own yet, and we won't pretend to.
The WaterKnown team
How we work
Written by people who read the reports
WaterKnown is written and maintained by our editorial team. We are not toxicologists, and we do not claim to be. What we do is read primary sources carefully, cite every number, and defer to the agencies whose job this actually is.
We work from primary sources
Utility Consumer Confidence Reports, EPA UCMR 5 occurrence data, EPA SDWIS, and NSF certification listings. Never aggregators, never a competitor's summary.
We defer on health questions
For what contaminants do to people, we point to EPA, ATSDR and CDC rather than paraphrasing them into something new.
We show our working
The scoring formula is published in full, every figure links to its report, and when a number cannot be read without guessing, the page says so instead.
Common questions
Straight answers about the ratings
Where does your data come from?
Do you test the water yourselves?
Do brands pay to be rated?
What does a score of 80 actually mean?
My city isn't listed. Can you add it?
How often does the data update?
Stop guessing at your water.
Look up your city, check the bottle in your fridge, or see what a filter is actually certified to remove.