Among states with at least 10 water systems in our data, Michigan has the highest average tap water score (83 out of 100, a B), followed closely by Oregon (82.9) and Indiana (79.9). New Jersey has the lowest average (55.7, a D), with Wisconsin, Arizona and Massachusetts close behind at about 60 to 61. Nationally, the 1,000 large systems we grade average 68.3, a C.
Below you’ll find every state’s average and median score, its grade breakdown, and the highest- and lowest-graded system in each state, with links to the full utility pages.
Read this first: what these state numbers cover
TapWaterSafety.org grades 1,000 public water systems, each serving more than 50,000 people (the smallest serves about 53,300). That is only a slice of the country’s public water systems. Most US systems are much smaller, and none of them are included here. So a state’s average describes its larger systems on our site, not every tap in the state.
Coverage is also uneven. California has 176 systems in our data, while some states have one or two. We rank only the 29 states with 10 or more systems (903 systems in total) and list the other 23 states and territories separately, because one utility can swing a small state’s average a lot.
What a grade measures
Each system gets a score from 0 to 100, which maps to a letter: A is 85 to 100, B 75 to 84, C 65 to 74, D 55 to 64, and F 54 or below. The score combines five parts, as described on our methodology page:
- Health guideline performance (40%): detected contaminant levels compared with EWG health guidelines, which are usually much stricter than legal limits.
- Legal compliance (20%): health-based EPA violations in the last three years.
- High-risk contaminants (20%): whether PFAS, lead, arsenic, chromium-6, radium, elevated nitrate or high disinfection byproducts were detected.
- Compliance and reporting history (10%): monitoring, reporting and public-notice violations.
- Source water vulnerability (10%).
So a low grade usually means contaminants were found above strict health guidelines, not that a utility broke the law. A system can be fully compliant with EPA rules and still score a D. For more on that gap, see EWG vs. EPA: the gap.
EPA compliance data used in the grades comes from EPA ECHO compliance records, checked October 7, 2026; last 12 quarters.
The national picture
| Grade | Systems | Share |
|---|---|---|
| A (85–100) | 77 | 7.7% |
| B (75–84) | 251 | 25.1% |
| C (65–74) | 319 | 31.9% |
| D (55–64) | 219 | 21.9% |
| F (0–54) | 134 | 13.4% |
The average score is 68.3 and the median is 69. About one in three systems (328) earns an A or B, and about the same number (353) gets a D or F.
States ranked by average score
States with at least 10 systems in our data, ranked by average score. The letter in parentheses is the grade that average score would earn. “Highest” and “lowest” are the top- and bottom-scoring systems in that state; ties are both listed. Click a state to see all of its graded systems.
| Rank | State | Systems | Avg. score | Median | A / B / C / D / F | Highest graded | Lowest graded |
|---|---|---|---|---|---|---|---|
| 1 | Michigan | 29 | 83.0 (B) | 88 | 19 / 5 / 4 / 1 / 0 | Lansing Board of Water & Light (A, 92) | Kalamazoo (D, 60) |
| 2 | Oregon | 14 | 82.9 (B) | 85 | 9 / 3 / 1 / 1 / 0 | Eugene Water & Electric Board (A, 89) / Gresham, City of (A, 89) | Portland Water Bureau (D, 64) |
| 3 | Indiana | 16 | 79.9 (B) | 81.5 | 6 / 6 / 3 / 1 / 0 | Indiana American Water - S. Indiana (A, 90) | South Bend Water Works (D, 64) |
| 4 | Maryland | 11 | 79.6 (B) | 78 | 4 / 2 / 5 / 0 / 0 | Glen Burnie-Broadneck (A, 94) | City of Baltimore (C, 67) |
| 5 | Tennessee | 30 | 77.5 (B) | 77 | 2 / 21 / 7 / 0 / 0 | Memphis Light, Gas, & Water (A, 87) | Kingsport Water Dept (C, 65) |
| 6 | Georgia | 30 | 75.2 (B) | 76 | 2 / 18 / 7 / 3 / 0 | Houston County-Feagin Mill (A, 93) | Clayton County Water Authority (D, 56) |
| 7 | Missouri | 12 | 74.4 (C) | 74 | 0 / 6 / 6 / 0 / 0 | Independence PWS (B, 83) | St Charles County PWSD 2 (C, 65) |
| 8 | Virginia | 25 | 72.8 (C) | 77 | 0 / 13 / 8 / 4 / 0 | JCSA - Central System (B, 84) | Western Virginia Water Authority (D, 62) |
| 9 | Florida | 93 | 71.7 (C) | 73 | 6 / 38 / 27 / 13 / 9 | Regional Utilities Water System (A, 93) | Lauderhill, City of (F, 44) |
| 10 | Louisiana | 15 | 71.3 (C) | 76 | 1 / 8 / 3 / 1 / 2 | Baton Rouge Water Company (A, 88) | Shreveport Water System (F, 45) |
| 11 | Minnesota | 18 | 70.9 (C) | 71 | 0 / 8 / 6 / 4 / 0 | Eagan (B, 83) | Saint Paul Regional Water Services (D, 55) |
| 12 | Ohio | 25 | 69.8 (C) | 70 | 1 / 3 / 16 / 5 / 0 | Hamilton Public Water System (A, 85) | Akron City PWS (D, 57) |
| 13 | Alabama | 16 | 69.6 (C) | 68.5 | 2 / 2 / 7 / 4 / 1 | Anniston, Water Works & Sewer Board of the City of (A, 87) | Mobile Board of Water & Sewer Commissioners (F, 53) |
| 14 | South Carolina | 14 | 69.5 (C) | 67 | 0 / 5 / 5 / 4 / 0 | BCWSA Sangaree W/D (0820002) (B, 81) | BJW&SA (0720003) (D, 57) |
| 15 | Washington | 36 | 69.2 (C) | 71 | 0 / 15 / 9 / 9 / 3 | Renton, City of (B, 83) | Kennewick, City of (F, 47) |
| 16 | Colorado | 24 | 68.6 (C) | 73 | 1 / 8 / 7 / 4 / 4 | Pueblo Board of WW (A, 87) | Thornton, City of (F, 44) |
| 17 | Iowa | 11 | 68.2 (C) | 69 | 0 / 2 / 5 / 3 / 1 | Cedar Rapids Water Department (B, 82) | Sioux City Water Supply (F, 49) |
| 18 | Pennsylvania | 30 | 67.5 (C) | 70 | 0 / 7 / 14 / 5 / 4 | Easton Area Water System (B, 80) | Aqua PA Main System (F, 43) |
| 19 | Illinois | 28 | 66.5 (C) | 69 | 0 / 5 / 13 / 9 / 1 | Palatine (B, 77) / IL American-West Suburban (B, 77) | Elgin (F, 49) |
| 20 | Connecticut | 10 | 66.4 (C) | 68 | 0 / 2 / 4 / 3 / 1 | New Britain Water Department (B, 78) | CTWC - Northern Reg-Western System (F, 53) |
| 21 | Utah | 19 | 65.7 (C) | 64 | 1 / 1 / 7 / 8 / 2 | Logan City Water System (A, 89) | West Jordan City Water System (F, 53) |
| 22 | New York | 29 | 65.4 (C) | 67 | 0 / 6 / 10 / 9 / 4 | MVWA - Mohawk Valley Water Authority (B, 79) | Veolia Water New York (F, 47) |
| 23 | Texas | 76 | 64.0 (D) | 65 | 0 / 7 / 33 / 26 / 10 | City of Bryan (B, 80) | City of Midland Water Purification Plant (F, 44) |
| 24 | California | 176 | 62.7 (D) | 64 | 3 / 28 / 54 / 40 / 51 | Helix Water District (A, 89) | Monterey Park-City, Water Dept. (F, 39) |
| 25 | North Carolina | 29 | 62.6 (D) | 61 | 0 / 4 / 7 / 14 / 4 | Hendersonville, City of (B, 81) | Harnett Regional Water (F, 50) |
| 26 | Massachusetts | 30 | 60.7 (D) | 59.5 | 1 / 0 / 9 / 11 / 9 | Upper Cape Regional Water Cooperative (A, 95) | Somerville Water Dept. (MWRA) (F, 46) |
| 27 | Arizona | 21 | 60.7 (D) | 62 | 0 / 1 / 8 / 6 / 6 | Arizona Water Co - Apache Junction (B, 76) | Liberty Water LPSCO (F, 43) / Avondale, City of (F, 43) |
| 28 | Wisconsin | 11 | 60.0 (D) | 61 | 0 / 0 / 3 / 6 / 2 | Milwaukee Waterworks (C, 67) | Racine Waterworks (F, 53) / Waukesha Water Utility (F, 53) |
| 29 | New Jersey | 25 | 55.7 (D) | 55 | 0 / 2 / 4 / 7 / 12 | NJ American Water - Ocean City (B, 80) | Trenton Water Works (F, 33) |
What stands out
PFAS detections drive many of the low grades. 392 of the 1,000 systems list “PFAS contamination” among their top concerns. Those systems average 59.2, compared with 74.2 for the rest, and they account for 121 of the 134 F grades. States where PFAS shows up often rank low: 22 of 25 New Jersey systems and 28 of 30 Massachusetts systems list it. In Michigan, only 6 of 29 do. Our PFAS rule explainer covers the federal limits.
Michigan stands out at the top. Nineteen of Michigan’s 29 large systems earn an A. That is 19 of the 77 A grades in the entire dataset, a quarter of them from one state.
Big states land in the middle or below. Florida (93 systems) averages 71.7, a C. Texas (76 systems) averages 64.0, and California (176 systems) averages 62.7, both D. California has the most F grades of any state (51), though it also has by far the most systems in our data.
Fifteen ranked states have no A-graded system, including Texas, New York, Pennsylvania, Illinois, Arizona and New Jersey. Eleven ranked states have no F, including Michigan, Oregon, Tennessee, Georgia and Virginia.
Grades and violation counts tell different stories. Florida has the most EPA “serious violators” in our data, yet its average grade is ninth of 29. That’s because most of its violations are monitoring and reporting problems, which make up only 10% of the score. California is the reverse: few violations but many low grades, mostly from contaminant detections. For violation-based rankings, see states ranked by drinking water violations.
Groundwater systems score a bit higher on average. Systems listed as groundwater (including purchased groundwater) average 71.9, compared with 67.2 for surface water systems. Our post on groundwater vs. surface water quality explains the trade-offs.
States and territories with fewer than 10 systems
These are not ranked because the samples are too small. Puerto Rico, Guam and Maine have high averages, but they rest on eight, one and one systems. Vermont has no system in our data.
Why a state average can mislead
- It reflects only larger systems. Small town systems and private wells are not graded here. If you are on a well, see our well water testing guide.
- One state can contain A and F systems side by side. Florida has six A grades and nine F grades. Your own utility’s grade matters far more than your state’s average.
- Grades depend on available data. Contaminant results come from EWG’s Tap Water Database, utility Consumer Confidence Reports and EPA monitoring. A system that tests for more contaminants, or reported more recently, may show more detections.
- Health guidelines are not legal limits. Many detections that lower a grade are far below what EPA allows. Whether to act on them is a personal choice; our post on whether tap water is safe to drink walks through how to think about it.
What to do next
- Find your own system. Use our search page or the states index. Each utility page lists its grade, top concerns and EPA record.
- Look at the top concerns, not just the letter. A D driven by disinfection byproducts calls for a different response than a D driven by PFAS or arsenic.
- Read your utility’s Consumer Confidence Report. Our guide to how to read your water quality report explains the tables.
- If you choose a filter, match it to the contaminant and check the certifier’s listing (NSF, IAPMO, WQA, CSA or UL) for that specific claim. Our guide to NSF filter certifications explains what to look for.
For the biggest systems in the country, see the 50 largest US water systems, graded.
Note: grades and EPA records reflect data as of October 7, 2026. A utility may have resolved issues or changed treatment since then. Check its EPA ECHO report or its latest Consumer Confidence Report for current status.
Sources
- TapWaterSafety.org: Methodology
- EPA ECHO: Safe Drinking Water Act Resources and FAQs
- EPA ECHO: Detailed Facility Reports (linked from each utility page)
- EWG Tap Water Database