Drinking water quality · 2024
· Verified
What's in Derby, CT tap water
28 contaminants were measured in the Derby, CT water system's 2024 annual report. Each is shown below against its federal limit — 2 sit at or above that limit.
- Reporting year
- 2024
- Contaminants measured
- 28
- Over federal limit
- 2
- Approaching the limit
- 0
- Worst contaminant
- PFOS
- Service area
- CT
PFAS — EPA UCMR5 (2023–2025)
2 PFAS compounds above EPA limits in Derby, CT
The EPA finalized the first-ever federal drinking-water limits for six PFAS compounds in April 2024. These numbers come straight from EPA's UCMR5 lab dataset — every U.S. system serving more than 3,300 people tested every PFAS sample at an entry point to its distribution system. PFAS not listed below were either tested and not detected, or not yet sampled.
PFOS (Perfluorooctane sulfonic acid)
● Over EPA limit (2.7×)near national p90 (19.900000000000006 ng/L across detecting U.S. systems)
PFOA (Perfluorooctanoic acid)
● Over EPA limit (1.8×)near national p90 (13.649999999999999 ng/L across detecting U.S. systems)
PFBS
● Detected (no federal limit)below national p90 (13.909999999999979 ng/L across detecting U.S. systems)
PFPeA
● Detected (no federal limit)below national p90 (15.95999999999999 ng/L across detecting U.S. systems)
Where your water comes from · EPA SDWIS
Derby, CT's drinking water comes from ground water, drawn from 37 sources.
Source
- NORTH SLEEPING GIANT · 5
- NORTH CHESHIRE · 4
- SEYMOUR · 4
- LAKE DAWSON · 2
- + 16 more
Treatment
- LAKE GAILLARD TREATMENT PLANT
- LAKE SALTONSTALL WATER TREATMENT PLANT
- LAKE WHITNEY WATER TREATMENT PLANT
- + 9 more
Distribution
Also buys water from SOUTHINGTON WATER DEPARTMENT, AQUARION-VALLEY, and 3 more.
Historical readings · EPA Six-Year Review (2012–2019)
4 contaminants historically over EPA limits in Derby, CT
Every U.S. public water system reports compliance-monitoring data to EPA. The Six-Year Review releases the 2012–2019 window as a single dataset — here's what your system reported, year by year. Values shown are the highest detection per analyte per year, compared to the federal MCL.
| Contaminant | Worst detection | EPA limit | Years (2012–2019) |
|---|---|---|---|
GROSS BETA worst: 2019 | 8.5 mrem/yr 2.1× | 4 mrem/yr | '19 |
TTHM worst: 2016 | 0.1227 mg/L 1.5× | 0.08 mg/L | '12'13'14'15'16'17'18'19 |
HAA5 worst: 2016 | 0.0729 mg/L 1.2× | 0.06 mg/L | '12'13'14'15'16'17'18'19 |
NITRATE NITRITE worst: 2013 | 10.3 mg/L 1.0× | 10 mg/L | '12'13'14'15'16'17'18'19 |
FLUORIDE worst: 2019 | 2.32 mg/L within | 4 mg/L | '12'13'14'15'16'17'18'19 |
NITRITE worst: 2016 | 0.448 mg/L within | 1 mg/L | '16'17 |
NITRATE worst: 2019 | 3.715 mg/L within | 10 mg/L | '12'13'14'15'16'17'18'19 |
RADIUM 226 228 worst: 2019 | 1.55 pCi/L within below national p90 | 5 pCi/L | '19 |
BARIUM worst: 2016 | 0.301 mg/L within above national p90 | 2 mg/L | '12'13'14'15'16'17'18'19 |
CHROMIUM worst: 2015 | 0.002 mg/L within below national p90 | 0.1 mg/L | '15'16'17'19 |
COPPER worst: 2012 | 0.34 mg/L below national p90 | — | '12'13'14'15'16'17'18'19 |
LEAD worst: 2012 | 0.07 mg/L | — | '12'13'14'15'16'17'18'19 |
DBAA worst: 2012 | 0.0007 mg/L | — | '12'13'14'15'16'18'19 |
DCAA worst: 2012 | 0.0235 mg/L | — | '12'13'14'15'16'17'18'19 |
MCAA worst: 2012 | 0.0054 mg/L | — | '12'13'14'15'16'17'18'19 |
TCAA worst: 2012 | 0.032600000000000004 mg/L | — | '12'13'14'15'16'17'18'19 |
BROMODICHLOROMETHANE worst: 2012 | 0.020399999999999998 mg/L | — | '12'13'14'15'16'17'18'19 |
BROMOFORM worst: 2012 | 0.0006 mg/L | — | '12'13'14'17'18 |
CHLOROFORM worst: 2012 | 0.096 mg/L | — | '12'13'14'15'16'17'18'19 |
DIBROMOCHLOROMETHANE worst: 2012 | 0.0055 mg/L | — | '12'13'14'15'16'17'18'19 |
Disinfectants
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| ChlorineA disinfectant added to drinking water to kill bacteria and viruses. | 1.4–2.7AverageAverage Level and Range Detected During 2024 | 4MRDL | Within the limit |
Inorganic chemicals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| ChlorideA naturally occurring salt compound. | 44.6–105AverageAverage Level and Range Detected During 2024 | 250MCL | Within the limit |
| Dibromoacetic acidA brominated haloacetic acid disinfection byproduct. | 0–0.9 ug/LReported levelSystem-wide | None set | Detected — no federal limit |
| Dichloroacetic acidA haloacetic acid disinfection byproduct. | 9.7–15.1 ug/LReported levelDistribution | None set | Detected — no federal limit |
| Monobromoacetic acidA brominated haloacetic acid disinfection byproduct. | 0–2.6 ug/LReported levelSystem-wide | None set | Detected — no federal limit |
| SulfateA naturally occurring mineral from rock and soil. | 12.9–38.6AverageAverage Level and Range Detected During 2024 | None set | Detected — no federal limit |
| Trichloroacetic acidA haloacetic acid disinfection byproduct. | 15.7–22.4 ug/LReported levelSystem-wide | None set | Detected — no federal limit |
Radionuclides
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| RadonA naturally occurring radioactive gas that can dissolve into groundwater. | 0–1856 pCi/LReported levelAverage Level and Range Detected During 2024 | 5000 pCi/LMCL | Within the limit |
Microbial
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Escherichia coli (E. coli)Escherichia coli — bacteria found in the gut of humans and animals. | 0MaximumLevel Detected During 2024 | 0MCL | None detected |
Metals
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| Antimony | 11Reported levelVolatile Organic Chemicals | None set | Detected — no federal limit |
| ManganeseA naturally occurring metal from soil and rock. | 0–0.21 mg/LReported levelAverage Level and Range Detected During 2024 | None set | Detected — no federal limit |
| SodiumA naturally occurring salt component. | 23.1–50.8 mg/LReported levelAverage Level and Range Detected During 2024 | None set | Detected — no federal limit |
Physical & aggregate
| Contaminant | Measured | Federal limit | Status |
|---|---|---|---|
| TOCTotal organic carbon — a measure of organic material dissolved in the water. | 1.92–2.59Reported levelAll Reservoirs | None set | Detected — no federal limit |
| TurbidityA measure of cloudiness from suspended particles in the water. | 0–2.1AverageRemoval Ratio During 2024 | None set | Detected — no federal limit |
People also ask about Derby, CT's water
+Is Derby, CT tap water safe to drink in 2024?
The 2024 Consumer Confidence Report for the Derby, CT water utility lists 2 contaminants at or above the federal limit: PFOS and PFOA. Whether that means the water is "unsafe" depends on which contaminant, how long the exposure, and individual health factors. The table on this page shows the measured value, the federal threshold, and the regulated statistic used for compliance.
+What contaminants are in Derby, CT tap water?
28 contaminants were measured in Derby, CT's 2024 Consumer Confidence Report, spanning inorganic chemicals, metals, and disinfection byproducts. 14 have an enforceable federal limit; the rest are detected but unregulated. Every measured value, in the utility's own units, is on this page.
+Which contaminants exceed federal limits in Derby, CT tap water?
2 contaminants in Derby, CT's 2024 report sit at or above the federal limit: PFOS (2.7× the limit); PFOA (1.8× the limit). The EPA enforces these limits against the regulated reporting statistic — typically a running annual average or 90th percentile — not a one-off sample spike.
+What is the worst contaminant in Derby, CT tap water?
The contaminant with the highest measured value relative to its federal limit in the 2024 report is PFOS, at 2.7× the federal threshold. It belongs to the pfas ("forever chemicals") family of contaminants.
+Where does the data on this page come from?
Every value is transcribed from Derby, CT's 2024 Consumer Confidence Report — the annual drinking-water report every U.S. public water utility is required by federal law to publish. The original source document is archived and viewable on this site. A water-quality report covers an entire service area, not a single address.
+How often is Derby, CT's water quality data updated?
Each U.S. public water utility publishes one Consumer Confidence Report per year, covering the prior calendar year's measurements. This page reflects the 2024 report; a new report will replace it once the utility publishes its next annual update.