No test yet? Get one first.
A $30–$200 water test beats a $1,500 guess. Your utility's annual water quality report (free, search "[your city] water quality report") covers regulated contaminants; a mail-in lab test (Tap Score, MyWaterTest) covers PFAS, lead and well-water minerals the utility doesn't have to report. Buy the filter after the test — never before.
Once you know your contaminants, size the system for your home's flow rate, then check the 5-year cost calculator before you buy. Our PFAS guide goes deep on "forever chemicals" specifically.