Do you need a water filter?
Check what your water system reported, then see what filtering would cost per year. Often the honest answer is: you don't need one.
No ZIP handy? Answer six questions about your house instead →
Start with the question you actually have
What is in my water?
Your system's PFAS and lithium results by ZIP, plus how to read your utility's annual water report.
Look up my ZIP → 2 · The costWhat would filtering cost?
Pitcher, faucet and under-sink filters per year and over five years, for the people in your house.
Calculate filter cost → 3 · The big systemIs reverse osmosis worth it?
Install cost, filter changes and the water it sends down the drain, against a simple pitcher.
Compare RO vs a pitcher →Worried about lead? Pitcher filters certified for lead · Faucet filters certified for lead · Lead and PFAS certifications explained
What "doing the math" looks like
A household of three drinking the EPA's average amount of tap water, using a popular pitcher filter. Every input is on the page, so you can swap in your own.
The same math for an under-sink filter, a faucet filter or bottled water is one click away in the filter cost calculator.
Sources: drinking water 0.23 gal per person per day, EPA Exposure Factors Handbook ch. 3, table 3-1; ZeroWater filter life 20 gal, IAPMO R&T listing W-17155 (read 20 Oct 2026); 6-pack $86.99, Target (read 21 Oct 2026). Prices change; the calculator shows the latest we checked.
Why you can check us
Every number has a source
Federal data, certification listings and dated retailer prices, named next to the figure. Methodology
We earn nothing
No ads, no affiliate links, no data sales. Retailer links are plain links. How we make money: we don't
We correct in public
Every change and every mistake we fixed, with the date. Corrections log
"Buy nothing" is an answer
If your water report is clean and your pipes are new, our tools say so.
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