No open health-based violations on EPA record in the last 10 years.
Serves about 14,693 people (6,319 connections) with surface water bought from Metropolitan District Commission.
From EPA's record for CT0520011. PurityMap is independent of CTWC.
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2 health-based violations in the last 10 years, from EPA's SDWIS compliance database.
| Period | Contaminant | Measured | Legal limit | EPA status |
|---|---|---|---|---|
| From May 2026 | Groundwater Rule | – | – | Archived |
| From November 2019 | Groundwater Rule | – | – | Resolved |
EPA required this system to test for 30 unregulated and emerging contaminants, from March 2023 to December 2023.
| Contaminant | Result | Limit | Status | Sampled | Source |
|---|---|---|---|---|---|
| Perfluorooctanesulfonic acid (PFOS) | 6 ng/L | 4.0 ng/L federal MCL (2024) | Above a historical reference; current applicability unverified | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| Perfluorooctanoic acid (PFOA) | 6 ng/L | 4.0 ng/L federal MCL (2024) | Above a historical reference; current applicability unverified | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| Perfluorohexanesulfonic acid (PFHxS) | 3 ng/L | 10 ng/L federal MCL (2024) | Within a historical reference; current applicability unverified | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| Perfluorohexanoic acid (PFHxA) | 4 ng/L | 400,000 ng/L Michigan EGLE state MCL (strictest US state) | Within a historical reference; current applicability unverified | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| Perfluorobutanoic acid (PFBA) | 7 ng/L | No federal or state limit; shown for transparency | Detected, no limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| Perfluoropentanoic acid (PFPeA) | 4 ng/L | No federal or state limit; shown for transparency | Detected, no limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| 11-Chloroeicosafluoro-3-oxaundecane-1-sulfonic acid (11Cl-PF3OUdS) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| 1H, 1H, 2H, 2H-perfluorodecane sulfonic acid (8:2 FTS) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| 1H, 1H, 2H, 2H-perfluorohexane sulfonic acid (4:2 FTS) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| 1H, 1H, 2H, 2H-perfluorooctane sulfonic acid (6:2 FTS) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| 4,8-Dioxa-3H-perfluorononanoic acid (ADONA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| 9-Chlorohexadecafluoro-3-oxanone-1-sulfonic acid (9Cl-PF3ONS) | < 2 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| Hexafluoropropylene oxide dimer acid (HFPO-DA) (GenX chemicals) | < 5 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| Lithium | < 9 µg/L | 10 µg/L EPA health reference level (screening, not a legal limit)Screening level, not a legal limit | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| N-ethyl perfluorooctanesulfonamidoacetic acid (NEtFOSAA) | < 5 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| N-methyl perfluorooctanesulfonamidoacetic acid (NMeFOSAA) | < 6 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| Nonafluoro-3,6-dioxaheptanoic acid (NFDHA) | < 20 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| Perfluoro (2-ethoxyethane) sulfonic acid (PFEESA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| Perfluoro-3-methoxypropanoic acid (PFMPA) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| Perfluoro-4-methoxybutanoic acid (PFMBA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| Perfluorobutanesulfonic acid (PFBS) | < 3 ng/L | 2,000 ng/L EPA health advisory (screening, not a legal limit)Screening level, not a legal limit | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| Perfluorodecanoic acid (PFDA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| Perfluorododecanoic acid (PFDoA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| Perfluoroheptanesulfonic acid (PFHpS) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| Perfluoroheptanoic acid (PFHpA) | < 3 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| Perfluorononanoic acid (PFNA) | < 4 ng/L | 10 ng/L federal MCL (2024) | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| Perfluoropentanesulfonic acid (PFPeS) | < 4 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| Perfluorotetradecanoic acid (PFTA) | < 8 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| Perfluorotridecanoic acid (PFTrDA) | < 7 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
| Perfluoroundecanoic acid (PFUnA) | < 2 ng/L | No federal or state limit; shown for transparency | Not detected above the reporting limit | 2023-03-21 to 2023-12-06 | UCMR5 Analytical Results: CTWC - UNIONVILLE SYSTEM (CT0520011) |
Screening tells you if something is worth a closer look; a lab result is the number you can act on.
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Screening: quick check, not lab-grade
Safe Home (EnviroTestKits)
Lead, read as one of three ranges: 0–4, 5–15 or 15+ ppb
Turnaround: 5 minutes
What it can't tell you: It shows a lead range, not an exact level, and tests nothing else unless you pay extra for the optional lab test.
Lab-certified results
ETR Laboratories
50+ substances, including lead, copper, arsenic, nitrate, hardness and coliform bacteria
Environmental Testing and Research Laboratories (ETR Labs), Leominster, MA · ISO/IEC 17025:2017, ANAB certificate AT-2638 · 2–4 business days after the lab receives it
What it can't tell you: It does not test PFAS, and not every result on the panel falls under the lab's accredited scope.
Get PurityMap updates about this water system.
Follow this water →CTWC's phone number on EPA record is 860-664-6125. Its mailing address is 93 West Main Street, CLINTON, CT 06413.
According to EPA's record, CTWC uses surface water bought from Metropolitan District Commission.
EPA's record shows 2 health-based violations for CTWC in the 10 years to July 9, 2026. No open health-based violations on EPA record in the last 10 years. EPA also lists 1 missed or late test or report in 10 years. The record comes from EPA's SDWIS compliance database.
The 90th-percentile lead result in CTWC's latest lead and copper round, which ended in December 2025, was 2.4 µg/L, below the federal action level of 15 µg/L.
PurityMap has no verified website for CTWC. Its phone number on EPA record is 860-664-6125. Its mailing address on EPA record is 93 West Main Street, CLINTON, CT 06413. Your water bill lists the ways to contact your supplier and pay. PurityMap does not take payments.