Systems reaching a study comparison level
45.9%28 of 61 active community water systems with complete monitoring
All 61 systems had complete monitoring. 28 reached at least one study comparison level; 33 did not. “Study comparison level” means the dated EPA technical cutoff used in this January 2026 research release. It does not determine household exposure, health risk, or current legal compliance.
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Find your water system
ZIP codes are used only to route visitors to public water systems that reported serving them. Confirm the actual provider using a water bill or utility record.
Compound summary
System counts in Connecticut
Each count shows how many included water systems reached the named study level.
| Study comparison | Systems reaching level | Water systems included | Percent |
|---|---|---|---|
| PFOA: study level 4.05 ppt (April 2024 EPA level: 4 ppt) | 25 | 61 | 41.0% |
| PFOS: study level 4.05 ppt (April 2024 EPA level: 4 ppt) | 20 | 61 | 32.8% |
| PFHxS: study level 15 ppt (April 2024 EPA level: 10 ppt) | 0 | 61 | 0.0% |
| PFNA: study level 15 ppt (April 2024 EPA level: 10 ppt) | 0 | 61 | 0.0% |
| HFPO-DA: study level 15 ppt (April 2024 EPA level: 10 ppt) | 0 | 61 | 0.0% |
| Hazard Index: study level 1.5 with at least two detected components (April 2024 EPA level: 1) | 0 | 61 | 0.0% |
System directory
Community water systems with complete monitoring
Each PWSID appears once, preventing double counting across ZIP associations.
| Public water system | PWSID | Population served | Primary source | Sampling locations | Study comparison |
|---|---|---|---|---|---|
| AQUARION WATER CO OF CT-GREENWICH SYSTEM | CT0570011 | 53,297 | Surface water | 3 | Reached a study level |
| AQUARION WATER CO OF CT-LITCHFIELD SYS | CT0740011 | 3,097 | Surface water purchased | 3 | Below the study levels |
| AQUARION WATER CO OF CT-MAIN SYSTEM | CT0150011 | 351,756 | Surface water | 5 | Below the study levels |
| AQUARION WATER CO OF CT-MYSTIC | CT1370011 | 10,788 | Surface water | 2 | Below the study levels |
| AQUARION WATER CO OF CT-NEW CANAAN SYS | CT0900011 | 10,097 | Surface water purchased | 1 | Below the study levels |
| AQUARION WATER CO OF CT-NEW MILFORD | CT0960011 | 13,331 | Ground water | 5 | Reached a study level |
| AQUARION WATER CO OF CT-NEWTOWN SYSTEM | CT0970011 | 6,054 | Ground water | 2 | Reached a study level |
| AQUARION WATER CO OF CT-NOROTON SYSTEM | CT0350011 | 18,737 | Surface water purchased | 2 | Below the study levels |
| AQUARION WATER CO OF CT-RIDGEFIELD SYS | CT1180011 | 7,476 | Surface water purchased | 4 | Reached a study level |
| AQUARION WATER CO OF CT-SIMSBURY SYSTEM | CT1280021 | 14,691 | Ground water | 3 | Below the study levels |
| AQUARION WATER CO OF CT-STAMFORD | CT1350011 | 119,214 | Surface water | 2 | Below the study levels |
| AQUARION WATER CO OF CT-TLWC WOODRICH | CT1666011 | 72 | Ground water | 1 | Reached a study level |
| AQUARION WATER CO OF CT-VALLEY SYSTEM | CT1240011 | 13,080 | Surface water purchased | 4 | Reached a study level |
| Avon Water Co. | CT0040011 | 11,590 | Ground water | 6 | Reached a study level |
| BERLIN WATER CONTROL COMMISSION | CT0070021 | 5,128 | Surface water purchased | 3 | Below the study levels |
| BETHEL WATER DEPT | CT0090011 | 9,507 | Surface water | 1 | Reached a study level |
| BRISTOL WATER DEPARTMENT | CT0170011 | 52,079 | Surface water | 4 | Reached a study level |
| COLCHESTER SEWER & WATER COMMISSION | CT0280011 | 4,020 | Ground water | 4 | Reached a study level |
| CROMWELL FIRE DISTRICT WATER DEPARTMENT | CT0330011 | 14,316 | Ground water | 1 | Below the study levels |
| CTWC - COVENTRY HILLS DIV | CT0320091 | 700 | Ground water | 1 | Below the study levels |
| CTWC - CRYSTAL SYSTEM | CT0690011 | 6,378 | Ground water | 2 | Reached a study level |
| CTWC - NAUGATUCK REG-COLLINSVILLE SYS | CT0230011 | 6,324 | Surface water | 2 | Reached a study level |
| CTWC - NAUGATUCK REG-TERRYVILLE SYSTEM | CT1110011 | 5,607 | Ground water | 2 | Below the study levels |
| CTWC - NAUGATUCK REG-THOMASTON SYSTEM | CT1400011 | 3,789 | Ground water | 1 | Below the study levels |
| CTWC - NAUGATUCK REGION-CENTRAL SYSTEM | CT0880011 | 22,735 | Surface water | 1 | Below the study levels |
| CTWC - NORTHERN REG-WESTERN SYSTEM | CT0473011 | 101,313 | Surface water | 7 | Reached a study level |
| CTWC - SHORELINE REGION-CHESTER SYSTEM | CT0261031 | 5,030 | Surface water | 2 | Below the study levels |
| CTWC - SHORELINE REGION-GUILFORD SYSTEM | CT0608011 | 33,975 | Surface water | 10 | Reached a study level |
| CTWC - UNIONVILLE SYSTEM | CT0520011 | 14,693 | Surface water purchased | 4 | Reached a study level |
| DANBURY WATER DEPARTMENT | CT0340011 | 62,055 | Surface water | 2 | Reached a study level |
| EAST LYME WATER & SEWER COMMISSION | CT0450011 | 15,245 | Surface water purchased | 6 | Reached a study level |
| GROTON UTILITIES | CT0590011 | 30,200 | Surface water | 1 | Below the study levels |
| HAZARDVILLE WATER COMPANY | CT0490021 | 18,544 | Ground water | 6 | Reached a study level |
| HERITAGE WATER COMPANY | CT1300021 | 7,300 | Surface water purchased | 2 | Below the study levels |
| JEWETT CITY WATER COMPANY | CT0580011 | 6,840 | Surface water | 2 | Below the study levels |
| KENSINGTON FIRE DISTRICT | CT0070011 | 7,553 | Surface water purchased | 2 | Below the study levels |
| MANCHESTER WATER DEPARTMENT | CT0770021 | 51,198 | Surface water | 7 | Reached a study level |
| MERIDEN WATER DIVISION | CT0800011 | 58,441 | Surface water | 7 | Reached a study level |
| METROPOLITAN DISTRICT COMMISSION | CT0640011 | 390,887 | Surface water | 3 | Below the study levels |
| MIDDLETOWN WATER DEPARTMENT | CT0830011 | 41,019 | Surface water | 2 | Below the study levels |
| Mashantucket Pequot Water System | 010106001 | 22,171 | Groundwater under influence of surface water | 1 | Reached a study level |
| Mohegan Tribal Utility Authority | 010109005 | 31,961 | Surface water purchased | 1 | Below the study levels |
| NEW BRITAIN WATER DEPARTMENT | CT0890011 | 73,534 | Surface water | 1 | Below the study levels |
| NEW HARTFORD WATER DEPARTMENT | CT0920011 | 1,872 | Ground water | 2 | Below the study levels |
| NEW LONDON DEPT. OF PUBLIC UTILITIES | CT0950011 | 27,620 | Surface water | 1 | Below the study levels |
| NORWALK FIRST TAXING DISTRICT | CT1030011 | 40,256 | Surface water | 2 | Reached a study level |
| NORWICH PUBLIC UTILITIES | CT1040011 | 36,163 | Surface water | 3 | Reached a study level |
| PORTLAND WATER DEPARTMENT | CT1130011 | 5,010 | Surface water purchased | 1 | Below the study levels |
| PUTNAM WATER POLLUTION CONTROL AUTHORITY | CT1160011 | 7,300 | Surface water | 3 | Reached a study level |
| REGIONAL WATER AUTHORITY | CT0930011 | 418,900 | Surface water | 11 | Reached a study level |
| SOUTH NORWALK ELECTRIC & WATER | CT1030021 | 42,000 | Surface water | 1 | Below the study levels |
| SOUTHINGTON WATER DEPARTMENT | CT1310011 | 43,069 | Surface water | 7 | Reached a study level |
| TORRINGTON WATER COMPANY | CT1430011 | 37,915 | Surface water | 1 | Below the study levels |
| UNIVERSITY OF CONNECTICUT - MAIN CAMPUS | CT0780021 | 27,199 | Surface water purchased | 2 | Reached a study level |
| VALLEY WATER SYSTEMS, INC. | CT1100011 | 18,231 | Ground water | 2 | Reached a study level |
| WATERBURY WATER DEPARTMENT | CT1510011 | 107,271 | Surface water | 1 | Below the study levels |
| WATERFORD WPCA | CT1520071 | 16,578 | Surface water purchased | 1 | Below the study levels |
| WATERTOWN FIRE DISTRICT | CT1530011 | 6,718 | Ground water | 1 | Below the study levels |
| WATERTOWN WATER & SEWER AUTHORITY | CT1530021 | 9,972 | Surface water purchased | 1 | Below the study levels |
| WINDHAM WATER WORKS | CT1630011 | 21,214 | Surface water | 1 | Below the study levels |
| WINSTED WATER WORKS | CT1620011 | 7,784 | Surface water | 1 | Below the study levels |
How the count works
What is included
Each active community water system with complete monitoring is counted once, even if it is linked with several ZIP codes. Private wells are excluded, and UCMR 5 did not comprehensively monitor every small system. This page does not apply Connecticut's state-specific standards or determine compliance. Use the official state or territory drinking-water program for current regulatory information.