What was found in Darien's water
The level at the city's main supplier, the highest level anywhere in the city, the EPA limit for each, and where every figure comes from.
| Contaminant | Level vs EPA limit | Suppliers | Source |
|---|---|---|---|
| Fluoride | 1035.95 µg/L 26% of the EPA limit 4000 µg/L Highest in the city: NORTH REGIONAL WATER FAC · 770 people · 2017 | 1/6 | SYR4 |
| Copper | 203.5 µg/L 16% of the EPA limit 1300 µg/L Main supplier: DARIEN · 21,751 people · 2017
Highest in the city: 300 µg/L — STEEPLE RUN SBDV · 1,931 people · 2019 | 6/6 | SYR4 |
| Nitrate | 70 µg/L 0.7% of the EPA limit 10000 µg/L Highest in the city: NORTH REGIONAL WATER FAC · 770 people · 2019 | 1/6 | SYR4 |
| Nitrate-Nitrite | 70 µg/L 0.7% of the EPA limit 10000 µg/L Highest in the city: NORTH REGIONAL WATER FAC · 770 people · 2018 | 1/6 | SYR4 |
| TTHM | 60.78 µg/L 76% of the EPA limit 80 µg/L Main supplier: DARIEN · 21,751 people · 2019
Highest in the city: 62.245 µg/L — HOBSON VALLEY WATER SYSTEM · 400 people · 2019 | 6/6 | SYR4 |
| Lead | 49.105000000000004 µg/L 327% of the EPA limit, at the 95th percentile of samples — 15 µg/L Highest in the city: STEEPLE RUN SBDV · 1,931 people · 2019 | 4/6 | SYR4 |
| Chloroform | 37.85999999999999 µg/L No EPA limit set Main supplier: DARIEN · 21,751 people · 2019 | 6/6 | SYR4 |
| Total Haloacetic Acids (HAA5) | 25.959999999999994 µg/L 43% of the EPA limit 60 µg/L Main supplier: DARIEN · 21,751 people · 2019 | 5/6 | SYR4 |
| Monochloroacetic Acid | 20.979999999999983 µg/L No EPA limit set Main supplier: DARIEN · 21,751 people · 2019 | 3/6 | SYR4 |
| Bromodichloromethane | 16.12 µg/L No EPA limit set Main supplier: DARIEN · 21,751 people · 2019
Highest in the city: 18.439999999999998 µg/L — HOBSON VALLEY WATER SYSTEM · 400 people · 2019 | 6/6 | SYR4 |
| Trichloroacetic Acid | 14.099999999999994 µg/L No EPA limit set Main supplier: DARIEN · 21,751 people · 2019 | 5/6 | SYR4 |
| Dichloroacetic Acid | 12.579999999999998 µg/L No EPA limit set Main supplier: DARIEN · 21,751 people · 2019
Highest in the city: 13.94 µg/L — STEEPLE RUN SBDV · 1,931 people · 2019 | 5/6 | SYR4 |
| Dibromochloromethane | 7.663999999999998 µg/L No EPA limit set Main supplier: DARIEN · 21,751 people · 2019
Highest in the city: 7.97 µg/L — HOBSON VALLEY WATER SYSTEM · 400 people · 2019 | 6/6 | SYR4 |
| Barium | 3.3649999999999998 µg/L 0.2% of the EPA limit 2000 µg/L Highest in the city: NORTH REGIONAL WATER FAC · 770 people · 2017 | 1/6 | SYR4 |
| Xylenes, Total | 1.978 µg/L 0% of the EPA limit 10000 µg/L Highest in the city: NORTH REGIONAL WATER FAC · 770 people · 2019 | 1/6 | SYR4 |
| Dibromoacetic Acid | 1.6879999999999997 µg/L No EPA limit set Main supplier: DARIEN · 21,751 people · 2019
Highest in the city: 1.8679999999999999 µg/L — GLEN ELLYN HEIGHTS SUBDIVISION · 1,931 people · 2019 | 5/6 | SYR4 |
| Monobromoacetic Acid | 1.613 µg/L No EPA limit set Main supplier: DARIEN · 21,751 people · 2019
Highest in the city: 1.64 µg/L — GLEN ELLYN HEIGHTS SUBDIVISION · 1,931 people · 2019 | 4/6 | SYR4 |
| Bromoform | 0.5441 µg/L No EPA limit set Main supplier: DARIEN · 21,751 people · 2019
Highest in the city: 1.3371 µg/L — GLEN ELLYN HEIGHTS SUBDIVISION · 1,931 people · 2019 | 5/6 | SYR4 |
| Arsenic | 1 µg/L 10% of the EPA limit 10 µg/L Highest in the city: NORTH REGIONAL WATER FAC · 770 people · 2017 | 1/6 | SYR4 |
| Combined Radium (-226 And -228) | 0.2400 pCi/L 4.8% of the EPA limit 5 pCi/L Highest in the city: NORTH REGIONAL WATER FAC · 770 people · 2014 | 1/6 | SYR4 |
| Lead | 0.0014 mg/L 9.2% of the EPA limit 0.0150 mg/L Main supplier: DARIEN · 21,751 people · 2025 | 6/6 | LCR |
Each bar shows the measured level as a share of the EPA limit: green is
well under, amber is close to it, red is over. For lead and copper the
limit applies to exactly the 90th-percentile figure shown, so red there
means a real exceedance. For everything else the limit applies to a
running annual average while the figure is the 95th percentile of the
system's samples — over 100% is worth reading, but is not by itself a
violation.
Formal violations are listed separately.
These are the utilities' own EPA-reported results, not a city-wide
average. A detection means the lab measured the
substance — it isn't the same as exceeding a legal limit. Hover a source
tag to see the EPA program and years behind each figure.
Water suppliers serving Darien
| Supplier | Population served |
|---|---|
| DARIEN | 21,751 |
| SOUTHEAST REGIONAL WATER FACILITY | 6,940 |
| GLEN ELLYN HEIGHTS SUBDIVISION | 1,931 |
| STEEPLE RUN SBDV | 1,931 |
| NORTH REGIONAL WATER FAC | 770 |
| HOBSON VALLEY WATER SYSTEM | 400 |
Frequently asked questions about Darien tap water
Is Darien tap water safe to drink?
EPA testing detected 21 contaminants in the water serving Darien. A detection isn't the same as a violation — most detected levels are within federal limits. Check the level and source for each contaminant above, and your utility's annual Consumer Confidence Report for the official compliance status.
How many water suppliers serve Darien?
6 public water suppliers report drinking-water monitoring for Darien, Illinois to the EPA. Each is listed above with its population served.
What contaminants are in Darien's water?
The contaminants EPA monitoring detected in Darien include Fluoride, Copper, Nitrate, Nitrate-Nitrite, TTHM. The full list, with the level at the main supplier and the data source, is in the table above.
Where does this data come from?
Every figure is official EPA drinking-water monitoring — the Lead & Copper Rule, the UCMR-5 nationwide testing program, and the EPA Six-Year Review — not our own testing. Each number is labelled with its source and period.