Income and PFOA, PFOS and lead results in U.S. areas
2,975 ZIP code areas matched to one water system, grouped by median household income, and how often that system's results were above an EPA level. Correlation, not cause.
In the Under $50k income band, 8.4% of 285 areas had a system whose PFOA or PFOS averaged above 4.0 ppt. In the $150k or more band, 12.1% of 282. Correlation, not cause.
Areas, not households. Systems without results for a chart aren't counted in it.
Areas whose system's PFOA or PFOS averaged above 4.0 ppt
ACS 5-year 2020–2024, median household income (ZCTA, approximates ZIP).
Share of areas whose system has UCMR 5 PFOA and PFOS results and whose PFOA or PFOS average was above 4.0 ppt, the level EPA set in 2024. Not yet enforceable. Monitoring results, not violations.
Bar length is scaled to the largest share in this chart.
Correlation, not cause. The chart compares areas, not households. A ZIP code's income says nothing about any one home.
Areas whose system's lead 90th percentile was above 15 ppb
ACS 5-year 2020–2024, median household income (ZCTA, approximates ZIP).
Share of areas whose system has a lead 90th percentile in the window and whose figure was above EPA's 15 ppb action level. Above an action level isn't a violation. Counts are small, so read the counts.
Bar length is scaled to the largest share in this chart.
Correlation, not cause.
How an area was matched to a water system
- Matching: a ZCTA is matched to a community water system only when EPA's reported service-area boundary for that system covers at least 80% of the ZCTA's area. 4,776 of 33,642 ZCTAs meet that test. Every other ZCTA is left out, including ZCTAs where several systems overlap.
- Areas, not households: a system serves many ZCTAs, and a ZCTA's income says nothing about any one home. A system's result is repeated for each ZCTA it was matched to.
- Coverage differs by state, because EPA's boundary data does. The charts describe the matched areas, not the country.
- PFOA and PFOS: the exact average of all of the system's EPA UCMR 5 results, with non-detects counted as zero. The area counts as above if either average is above 4.0 ppt. Systems with no UCMR 5 result aren't in that chart.
- Lead: the system's latest lead 90th percentile since July 1, 2021 (EPA SDWIS, extract October 14, 2026). Systems with none in that window aren't in that chart.
- Income: ACS 5-year median household income by ZCTA. Only ZCTAs with a margin of error (90%) of at most 20% of the estimate and at least 1,000 residents are used; 2,975 of the 4,776 matched ZCTAs pass.
Left out of the 4,776 matched ZCTAs: 615 with no ACS income estimate, 1,047 with a margin of error above 20% of the estimate, and 139 with fewer than 1,000 residents.
Thresholds: a ZIP code is charted only if its ACS margin of error (90%) is at most 20% of its median income and it has at least 1,000 residents.
Matched areas by state
- CA 520
- TX 369
- NY 357
- NJ 207
- MA 139
- FL 126
- NC 118
- MO 116
The 8 states with the most matched areas. Some states have very few.
Correlation, not cause.
These utilities' PFOA or PFOS results averaged above 4.0 ppt, the level EPA set in 2024, not yet enforceable (water systems must meet it by April 2029; EPA has proposed allowing until 2031). Non-detects count as zero in the average.
Being above an action level isn't a violation; it requires steps like treatment and public education. EPA's lead action level is scheduled to become 10 ppb on Nov. 1, 2027; until then it is 15 ppb.
Sources: EPA UCMR 5 occurrence data (PFOA and PFOS); EPA SDWIS lead and copper results, via ECHO SDWA bulk download; EPA community water system service-area boundaries; U.S. Census Bureau, American Community Survey 5-year estimates (B19013, B01003).
Not a test of your tap. Water Scores are educational estimates from public data, not medical advice.
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Data as of . Rankings are updated monthly. Corrections are noted in each monthly update.