Tap Water Quality Report
Tap water quality in DARIEN, Connecticut
Tap water in DARIEN, Connecticut receives a grade of D (64/100) from TapWaterSafety.org. It's served by 2 public water systems, primarily AQUARION-STAMFORD. The most significant water quality concerns are: Haloacetic acids (HAA9) significantly above health guideline; Haloacetic acids (HAA5) significantly above health guideline; Total trihalomethanes (TTHMs) significantly above health guideline; PFAS contamination. Data sources: EPA SDWIS, EPA ECHO, EWG Tap Water Database.
What's in DARIEN's tap water
Top water quality concerns identified by the EPA and Environmental Working Group across the utilities serving DARIEN.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 42.0 ppb, 701x above the EWG health guideline of 0.06 ppb.
Haloacetic acids (HAA5) significantly above health guideline
Moderate concernHaloacetic acids (HAA5) detected at 37.2 ppb, 372x above the EWG health guideline of 0.1 ppb.
Total trihalomethanes (TTHMs) significantly above health guideline
Moderate concernTotal trihalomethanes (TTHMs) detected at 47.1 ppb, 314x above the EWG health guideline of 0.15 ppb.
PFAS contamination
Severe concernPerfluorooctane sulfonate (PFOS), Perfluorooctanoic acid (PFOA) detected. PFAS are persistent chemicals linked to cancer and immune effects with no known safe exposure threshold.
EPA compliance record
Official U.S. EPA records for AQUARION-STAMFORD (system ID CT1350011) for the last 3 years. Checked 2026-10-07.
Source: U.S. EPA Enforcement and Compliance History Online (ECHO), from the Safe Drinking Water Information System. See EPA's full report.
Water systems serving DARIEN
DARIEN is served by 2 public water systems. Click any utility to see its complete grade card and treatment plant contact info.
AQUARION-STAMFORD
- Haloacetic acids (HAA9) significantly above health guideline
- Haloacetic acids (HAA5) significantly above health guideline
- Total trihalomethanes (TTHMs) significantly above health guideline
AQUARION-EASTERN FAIRFIELD COUNTY
- PFAS contamination
- Haloacetic acids (HAA9) significantly above health guideline
- Total trihalomethanes (TTHMs) significantly above health guideline
Recommended filters for DARIEN
Filters matched to the specific contaminants in DARIEN's water supply.
Carbon filter certified for VOCs (NSF/ANSI 53)
$180-$599Activated carbon is effective for disinfection byproducts. Look for NSF/ANSI 53 VOC reduction.
Disclosure: TapWaterSafety earns a commission from purchases made through these links. This does not influence our scoring methodology or filter selection.
All contaminants detected in DARIEN's tap water
Every contaminant identified, compared side-by-side against US EPA legal limits, the EU Drinking Water Directive (2020/2184), WHO Guidelines, and California's Public Health Goal. Why we show multiple standards →
| Contaminant | Detected | EWG US health-based |
EPA US legal |
EU DWD Europe |
WHO global |
CA PHG strictest US |
Tested sample year |
Status |
|---|---|---|---|---|---|---|---|---|
| Haloacetic acids (HAA9) Disinfection byproduct |
58.1 ppb | 0.06 | — | — | — | — | — | 968× over |
| Haloacetic acids (HAA5) Disinfection byproduct |
37.2 ppb | 0.1 | 60.0 | 60 | — | — | — | 372× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
52.4 ppb | 0.15 | 80.0 | 100 | — | — | — | 349× over |
| Trichloroacetic acid Disinfection byproduct |
21.5 ppb | 0.1 | — | — | — | — | — | 215× over |
| Bromodichloromethane Disinfection byproduct |
10.0 ppb | 0.06 | — | — | — | — | — | 167× over |
| Chloroform Disinfection byproduct |
37.1 ppb | 0.4 | — | — | — | — | — | 93× over |
| Dichloroacetic acid Disinfection byproduct |
13.9 ppb | 0.2 | — | — | — | — | — | 70× over |
| Perfluorooctanoic acid (PFOA) PFAS |
1.66 ppt | 0.09 | 4.0 | 100 | 100 | 0.007 | — | 18× over |
| Dibromochloromethane Disinfection byproduct |
1.68 ppb | 0.1 | — | — | — | — | — | 17× over |
| Dibromoacetic acid Disinfection byproduct |
0.331 ppb | 0.03 | — | — | — | — | — | 11× over |
| Nitrate Inorganic |
0.765 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 5.5× over |
| Nitrate and nitrite Inorganic |
0.525 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 3.7× over |
| Chromium (hexavalent) Heavy metal |
0.0674 ppb | 0.02 | — | — | — | — | — | 3.4× over |
| Perfluorooctane sulfonate (PFOS) PFAS |
0.893 ppt | 0.3 | 4.0 | 100 | 100 | 1 | — | 3.0× over |
| Chlorate Disinfection byproduct |
137.1 ppb | 210.0 | — | — | — | — | — | Below guideline |
| Bromoform Disinfection byproduct |
0.0784 ppb | 0.5 | — | — | — | — | — | Below guideline |
| Manganese Heavy metal |
10.4 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| Monochloroacetic acid Disinfection byproduct |
1.59 ppb | 53.0 | — | — | — | — | — | Below guideline |
| Barium Heavy metal |
20.0 ppb | 700.0 | 2000.0 | — | 1300 | 2000 | — | Below guideline |
| Vanadium Other |
0.383 ppb | 21.0 | — | — | — | — | — | Below guideline |
| Monobromoacetic acid Disinfection byproduct |
0.134 ppb | 25.0 | — | — | — | — | — | Below guideline |
| Perfluorobutanoic Acid (PFBA) PFAS |
1.47 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Perfluorohexanoic Acid (PFHxA) PFAS |
0.807 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Perfluoropentanoic Acid (PFPeA) PFAS |
0.75 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Perfluoroheptanoic acid (PFHPA) PFAS |
0.279 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Perfluorobutane sulfonate (PFBS) PFAS |
0.293 ppt | 2000.0 | — | — | — | — | — | Below guideline |
| Strontium Radiological |
0.0739 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| Fluoride Inorganic |
0.325 ppm | — | 4.0 | 1.5 | 1.5 | — | — | Below guideline |
All values in the unit of the detected level. Red cells indicate the detected level exceeds that standard. Some contaminants have limits in some jurisdictions but not others (shown as —). The "Tested" column shows the year each contaminant sample was collected.
Sources: US EPA, EU Drinking Water Directive 2020/2184, WHO Guidelines, California OEHHA PHGs, EWG Tap Water Database.
Treatment plant contact info
For service issues, water quality concerns, or to request a Consumer Confidence Report from AQUARION-STAMFORD.
General Contact
Treatment Plant
ZIP codes served
DARIEN's public water systems serve the following ZIP codes: