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18 cities ranked best to worst by EPA-record water quality score
Middletown has the best tap water grade in Connecticut (A, 100/100); Norwich is lowest (C, 71/100). Overall, none of the 18 Connecticut systems we grade has a health-based EPA violation in the last five years, so the state's tap water is safe by EPA compliance records — 61% earn a B or better.
This page ranks the 18 Connecticut cities whose water systems we have matched to EPA records. Every city starts at 100 points and loses points for health-based EPA violations in the last five years (SDWIS 2026Q2), its most recent Lead and Copper Rule 90th-percentile result, PFAS detected in EPA's 2023–2026 UCMR5 monitoring, and 2012–2019 compliance samples that averaged near or above a limit. Letters follow fixed bands (A ≥90, B ≥80, C ≥70, D ≥60, F below 60). Cities run from the highest score (Middletown) down to the lowest (Norwich); ties are ordered by population served. See the full scoring methodology for every deduction and the data vintages. 7 further Connecticut cities are listed at the bottom without a grade because we have not yet matched them to an EPA water system.
An A or B grade points to water that consistently tests within federal safety limits, while a C suggests moderate issues worth watching and a D or F flags contaminants or compliance problems serious enough to act on. These grades describe system-level water leaving the treatment plant — they can't account for your home's own plumbing, so older houses with lead service lines or fixtures can add contaminants after the water arrives. For a contaminant-by-contaminant view, see the Connecticut contaminant breakdown or drill into the county-level rankings.
What the EPA service line inventory and our Connecticut guide say, beyond the scores.
25 Connecticut cities have a report on this site. 18 of them are matched to an active EPA-registered community water system (PWSID). Those 18 systems report serving 1,939,787 people in EPA's Safe Drinking Water Information System (SDWIS).
Of 18 cities of the 25 Connecticut cities we can grade from EPA records, 11 cities (61%) grade B or better, 7 sit in the C range and 0 grade D or F. The average score is 87/100. 7 cities are not graded because they have not been matched to an EPA system yet.
None of the 18 graded systems has a health-based EPA violation in the last five years; the 10 violations on file in that window are monitoring or reporting lapses.
18 cities have a Lead and Copper Rule 90th-percentile result from 2020 or later: none at 5 ppb or more — every reported result is well below the action level.
EPA's UCMR5 PFAS monitoring (2023–2026) covers 18 cities: PFAS were detected in 10 cities, and PFOA or PFOS reached EPA's 4 ppt limit in 10 cities.
Groton scores highest (100) and Norwich lowest (71), a 29-point spread.
Because lead enters water after treatment, the most useful statewide number is the service line inventory Connecticut utilities filed with EPA (Q2 2026). 951 Connecticut systems inventoried 834,265 service lines: 7,993 confirmed lead plus 5,180 galvanized lines requiring replacement, spread across 35 systems. The bigger number is 281,399 lines (34%) whose material is still unknown — more than one line in four — and EPA treats unknown lines as possible lead until a utility verifies them.
Of the 18 city-linked Connecticut utilities with an inventory on file, 17 report at least one lead or galvanized-requiring-replacement line and 1 reports no lead with most lines verified. The largest, REGIONAL WATER AUTHORITY (New Haven, 418,900 served), reports 17 lead lines and 2,207 galvanized requiring replacement. The most lead lines among city-linked systems belong to AQUARION-EASTERN FAIRFIELD COUNTY (Shelton): 3,948.
| Contaminant | Federal limit | Cities elevated | Over limit | Highest reading | Why it matters |
|---|---|---|---|---|---|
| Total Trihalomethanes | EPA MCL 0.080 mg/L (80 ppb) | 12 | 0 | Norwich | Total Trihalomethanes is associated with liver, kidney and nervous-system effects and increased cancer risk over long exposure. |
| PFAS | EPA 2024 MCLs of 4.0 ppt for PFOA and PFOS | 10 | 10 | Norwich | PFAS are linked to immune, developmental, liver and some cancer effects. |
| Haloacetic Acids | EPA MCL 0.060 mg/L (60 ppb) for HAA5 | 5 | 0 | Waterbury | Haloacetic Acids is associated with increased cancer risk over long exposure. |
Service line counts: EPA SDWIS Service Line Inventory, Q2 2026 snapshot (updated 2026-08-18). Limits: EPA National Primary Drinking Water Regulations.
How Connecticut's 18 cities are distributed by water quality grade
11 out of 18 cities meet or exceed a B grade for water quality
Sorted by water quality score from best to worst. Click any city for a detailed water quality report.
| Rank | City | Score | Grade |
|---|---|---|---|
| 1 | Middletown | 100/100 | A |
| 2 | Torrington | 100/100 | A |
| 3 | Groton | 100/100 | A |
| #4 | New London | 100/100 | A |
| #5 | Naugatuck | 100/100 | A |
| #6 | Hartford | 99/100 | A |
| #7 | New Britain | 99/100 | A |
| #8 | Waterbury | 98/100 | A |
| #9 | Bristol | 88/100 | B |
| #10 | Stamford | 85/100 | B |
| #11 | Danbury | 83/100 | B |
| #12 | New Haven | 76/100 | C |
| #13 | Shelton | 74/100 | C |
| #14 | Enfield | 74/100 | C |
| #15 | Meriden | 73/100 | C |
| #16 | Norwalk | 73/100 | C |
| #17 | Manchester | 72/100 | C |
| #18 | Norwich | 71/100 | C |
Sources: EPA SDWIS/ECHO violations and Lead and Copper Rule results (2026Q2 extract), UCMR5 PFAS occurrence (2023–2026), SYR4 compliance samples (2012–2019). Rubric v2 — methodology.
Found your city above? These guides turn its grade into an action plan.
Pitcher vs. under-sink vs. reverse osmosis, matched to the contaminants reported in Connecticut systems.
Taste, odor, trihalomethanes, and why a carbon filter handles them
Where it comes from, how to test, and which filters are NSF 53 certified to remove it
Best filters for lead →EPA's inventory of lead pipes by water system — a risk these plant-level grades cannot capture.
Put a Connecticut city next to where you're moving from (or to) and see every contaminant head to head.
The best water quality in Connecticut is found in Middletown with a score of 100/100 and a grade of A. This puts Middletown among the top-performing cities in the country for drinking water safety.
The most concerning water quality is in Norwich scoring 71/100 with a grade of C. Residents may want to consider home water testing and filtration options.
The statewide average score is 87/100, which is 1 points below the national average of 88/100. Only 44% of Connecticut cities score above the national average, suggesting statewide water quality improvement is needed.
Connecticut tap water averages 87/100. Even with solid scores, a certified filter removes trace contaminants and improves taste — especially useful for households with young children or anyone sensitive to chlorine or lead.
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Middletown has the best water quality grade among the 18 Connecticut cities we can grade, with a score of 100/100 (grade A). Scores start at 100 and lose points for health-based EPA violations, lead 90th-percentile results, PFAS detections in EPA's UCMR5 monitoring and historical (2012–2019) readings near a limit. 5 cities share this top score; the largest system is listed first.
It varies by utility. Across the 18 Connecticut cities we grade from EPA records, the average score is 87/100 and 61% earn a B or better. None has a health-based EPA violation in the last five years. No city grades below C. Lead from household plumbing is not captured by any city-level grade.
By population served: New Haven grades C (76/100, #12 of 18); Hartford grades A (99/100, #6 of 18); Shelton grades C (74/100, #13 of 18); Stamford grades B (85/100, #10 of 18); Waterbury grades A (98/100, #8 of 18). Each city report lists the utility's violations, lead 90th-percentile result and PFAS results.
Of the 18 graded Connecticut cities, 0 cities have a D or F grade. Another 7 cities fall in the C range. 8 of 18 (44%) score above the national average of 88/100 across all graded U.S. cities in our dataset. 7 further Connecticut cities are not graded because we have not matched them to an EPA water system yet.
This page ranks 18 Connecticut cities from EPA's Safe Drinking Water Information System (violations and lead results, 2026Q2), UCMR5 PFAS monitoring (2023–2026) and Six-Year Review sample data (2012–2019). Each city link opens a report with the utility's violation history, lead 90th-percentile results and PFAS table. For official Consumer Confidence Reports (CCR), contact your local water utility — federal law requires all community water systems to deliver an annual CCR to customers. The Connecticut state environmental agency and the EPA's Safe Drinking Water Information System (SDWIS) also publish official water quality data.
State water quality summary and key statistics
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Compare water quality across all 50 states
Side-by-side water quality comparison
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