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Community Water System · PWS CT1360011

Sterling Water System

Oneco, Connecticut 06373 - drinking water served from groundwater sources to 308 people, tracked in EPA SDWIS and UCMR5.

308
People served
99
EPA violations
0
Health-based
Untested
UCMR5 result

The verdict

EPA records 99 drinking-water violations at Sterling Water System - above the Connecticut per-system average.

99
Total EPA violations on record
0%
Health-based (MCL / treatment failure)
308
People served by this system
N/A
PFAS compounds detected (UCMR5)

Water Quality Snapshot: Sterling Water System

Sterling Water System is a local-owned community water system that delivers drinking water to 308 residents in Oneco, Connecticut (Windham County) through 90 service connections. Its water is drawn from groundwater sources. EPA's Safe Drinking Water Information System records 99 total violations for this system , of which 0 (0%) are health-based, meaning a contaminant exceeded an EPA Maximum Contaminant Level or a required treatment technique failed. A further 88 monitoring and reporting violations are on file. The most recent violation on record dates to 2018.

The most frequently cited contaminant at this system is Lead and Copper Rule, recorded in 8 violations (MR). This system has not yet been sampled under EPA's UCMR5 PFAS monitoring program, so no PFAS detection data is available here.

Across Connecticut, EPA tracks 2,332 public water systems serving 2,886,005 people, with 206,662 cumulative violations and 21,779 health-based violations on record. About 94% of systems in the state carry at least one violation, and state-wide the average per system is 88.6 violations. Statewide, 40 of 63 UCMR5-tested systems have reported PFAS detections (63.5%).

Sterling Water System's 99 violations sit above the Connecticut average.

All figures above are sourced directly from EPA SDWIS and UCMR5 public data releases and are updated as EPA publishes new reporting cycles.

Population Served
308
Total Violations
99
Health-Based Violations
0
Water Source
Groundwater

System Details

System Type
Community
Owner Type
Local
Connections
90
County
Windham
School/Daycare
No
MCL Violations
0
Monitoring Violations
88
Treatment Tech Violations
0

Violation History

Contaminant violations recorded by EPA.

Contaminant Category Count Latest
Lead and Copper Rule MR 8 1994
TTHM MR 4 2018
Total Haloacetic Acids (HAA5) MR 4 2018
Endrin MR 2 2011
Diquat MR 2 2011
Di(2-ethylhexyl) adipate MR 2 2011
OXAMYL MR 2 2011
Simazine MR 2 2011
Di(2-ethylhexyl) phthalate MR 2 2011
Aldicarb sulfone MR 2 2011
Aldicarb MR 2 2011
Atrazine MR 2 2011
2,4-D MR 2 2011
2,4,5-TP MR 2 2011
HEXACHLOROBENZENE MR 2 2011
Benzo(a)pyrene MR 2 2011
Pentachlorophenol MR 2 2011
Total Polychlorinated Biphenyls (PCB) MR 2 2011
1,2-DIBROMO-3-CHLOROPROPANE MR 2 2011
Chlordane MR 2 2011
Combined Uranium MR 2 2011
Combined Radium (-226 and -228) MR 2 2011
ManMade Beta Particle and Photon Emitter MR 2 2011
Heptachlor MR 2 2011
Toxaphene MR 2 2011
Methoxychlor MR 2 2011
Gross Alpha, Excl. Radon and U MR 2 2011
Dalapon MR 2 2011
Carbofuran MR 2 2011
Gross Beta Particle Activity MR 2 2011

Verify This Water System

The figures above are aggregated from EPA's public databases. To verify the underlying records, or to file a complaint, request a Consumer Confidence Report, or check current monitoring status, go directly to the federal and state regulators that enforce the Safe Drinking Water Act for Sterling Water System.

Federal Source of Truth

EPA SDWIS, Federal Reports

EPA's Safe Drinking Water Information System (SDWIS) holds the federal compliance record for every regulated public water system. Open the system-level report by PWS ID:

View PWS ID CT1360011 on SDWIS

Source: EPA SDWIS Federal Reports Search

State Regulator

Connecticut Drinking Water Authority

Connecticut's primacy agency administers the Safe Drinking Water Act locally. Search EPA SDWIS for the current state contact, or use the state's public health or environment department portal.

Find CT regulator via EPA SDWIS

Violation Timeline

Each row links to the EPA SDWIS public record for verification. Cross-reference the contaminant code on EPA's federal report to see violation dates, return-to-compliance status, and enforcement actions.

Year (latest) Contaminant Category Count EPA Record
2018 TTHM MR 4 SDWIS / CT1360011 / 2950
2018 Total Haloacetic Acids (HAA5) MR 4 SDWIS / CT1360011 / 2456
2016 Consumer Confidence Rule Other 1 SDWIS / CT1360011 / 7000
2011 Endrin MR 2 SDWIS / CT1360011 / 2005
2011 Diquat MR 2 SDWIS / CT1360011 / 2032
2011 Di(2-ethylhexyl) adipate MR 2 SDWIS / CT1360011 / 2035
2011 OXAMYL MR 2 SDWIS / CT1360011 / 2036
2011 Simazine MR 2 SDWIS / CT1360011 / 2037
2011 Di(2-ethylhexyl) phthalate MR 2 SDWIS / CT1360011 / 2039
2011 Aldicarb sulfone MR 2 SDWIS / CT1360011 / 2044
2011 Aldicarb MR 2 SDWIS / CT1360011 / 2047
2011 Atrazine MR 2 SDWIS / CT1360011 / 2050
2011 2,4-D MR 2 SDWIS / CT1360011 / 2105
2011 2,4,5-TP MR 2 SDWIS / CT1360011 / 2110
2011 HEXACHLOROBENZENE MR 2 SDWIS / CT1360011 / 2274

How Sterling Water System Compares

Cross-reference this system's record against state averages and the federal MCL framework for context.

Metric Sterling Water System Connecticut avg Federal benchmark
Total violations 99 88.6 SDWA compliance, any non-zero count is a recorded breach
Health-based violations 0 9.3 Indicates a contaminant exceeded a federal MCL
PFAS detection None 63.5% EPA final rule (2024): PFOA/PFOS MCL = 4.0 ppt
Population served 308 1,238 Sizing context for compliance burden

Sources: EPA SDWIS and EPA National Primary Drinking Water Regulations (40 CFR Part 141). State averages computed across 2,332 regulated public water systems in Connecticut.

Federal MCL reference, Safe Drinking Water Act thresholds ▼
Contaminant Federal MCL / Action Level Note
Lead 0 mg/L (Action Level: 0.015 mg/L) Lead and Copper Rule treatment technique
Arsenic 0.010 mg/L (10 ppb) Health-based MCL since 2006
Total Coliform Treatment technique (RTCR) Indicator organism, monitoring trigger
PFOA / PFOS (PFAS) 4.0 ppt each (final 2024 rule) Compliance deadline 2029 (EPA proposed extending to 2031, not yet final as of May 2026)
Nitrate (as N) 10 mg/L Acute health risk for infants

Frequently Asked Questions

Is Sterling Water System water safe to drink? ▼
Sterling Water System (PWS ID: CT1360011) has 99 recorded violations in the EPA SDWIS database. No PFAS contamination was detected in UCMR5 testing. This system serves 308 people using Groundwater sources.
How many people does Sterling Water System serve? ▼
Sterling Water System serves 308 people in Oneco, Connecticut. It is a Local-owned system using Groundwater water sources with 90 service connections.
What type of violations does Sterling Water System have? ▼
Sterling Water System has 99 total violations: 0 health-based violations (MCL exceedances or treatment failures), 88 monitoring/reporting violations, and 0 treatment technique violations. Health-based violations indicate contaminant levels exceeded EPA safe limits.
Has PFAS been detected in Sterling Water System water? ▼
No PFAS testing data is available for Sterling Water System under the EPA's UCMR5 monitoring program.
What water source does Sterling Water System use? ▼
Sterling Water System uses Groundwater as its primary water source. It is classified as a Community Water System (CWS), serving residential populations year-round.
Where does this data come from? ▼
All data comes from the EPA Safe Drinking Water Information System (SDWIS) and the UCMR5 PFAS monitoring program. SDWIS tracks compliance for all public water systems regulated under the Safe Drinking Water Act.
Data Sources: EPA Safe Drinking Water Information System (SDWIS), Q4 2025. This data is provided for informational purposes only.

Read our methodology - how this data is sourced, computed, and verified.

Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial

Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This system's figures are rendered directly from EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.