Do Your Own Math

Do you need a water filter?

See what your public water system reported to the EPA, then compare the options per year. Buying nothing is one of them.

Not in the US? Choose your country · No ZIP? Answer six questions

Example result
New York City SystemNew York

None detected (below the reporting level)

Neither lithium nor any of the six PFAS shown was found above the laboratory reporting level in 112 samples, Oct 2023 – Jan 2025.

A public-system report, not a test of any one tap.

Buy nothing$0 a year

EPA UCMR 5, read 31 Oct 2026 · Open this page →

How it works

  1. 1Check your water systemEPA results for your system, with sample dates.
  2. 2Check the certificationA filter only reduces what it is certified for.
  3. 3Compare the cost per yearBuy nothing, pitcher, faucet or under-sink.

What the data covers

10,313 public water systems

20,768 ZIP codes matched to a system

EPA UCMR 5 results for six PFAS and lithium, samples 2023–2025, read 31 Oct 2026. How we compare results · Download the data (CC BY 4.0)

Browse by state

Alabama Arizona Arkansas California Colorado Connecticut District of Columbia Florida Georgia Hawaii Illinois Indiana Kansas Kentucky Louisiana Maryland Massachusetts Michigan Minnesota Missouri Nebraska Nevada New Jersey New Mexico New York North Carolina Ohio Oklahoma Oregon Pennsylvania Puerto Rico South Carolina Tennessee Texas Utah Virginia Washington Wisconsin

Why you can check us

Every number has a source and a date. Federal data, certification listings and dated retailer prices, named next to the figure.

There are no ads or affiliate links on this site.

We answer and correct in public. A question, or something we got wrong? Ask us or tell us, no account needed. Every fix goes on the corrections log.