Water Quality Report · Updated May 12, 2026
REGIONAL WATER AUTHORITY
REGIONAL WATER AUTHORITY delivers tap water graded D (55/100) by TapWaterSafety.org. The utility serves approximately 418,900 residents in ANSONIA, Connecticut using surface water. The most significant water quality concerns are: PFAS contamination; Haloacetic acids (HAA9) significantly above health guideline; Haloacetic acids (HAA5) significantly above health guideline; Total trihalomethanes (TTHMs) significantly above health guideline. For questions, the utility can be reached at 203-401-2710.
Is ANSONIA tap water safe to drink?
REGIONAL WATER AUTHORITY delivers tap water that earns a grade of D (55/100) from TapWaterSafety.org — a below-average rating, with multiple concerns including pfas contamination.
The utility serves 418,900 residents in ANSONIA and 19 other communities, drawing from surface water. Despite being legal under US EPA standards, this water would fail the European Union's Drinking Water Directive, primarily due to pfas contamination.
Public testing data identifies 15 contaminants in this water above EWG's health-based guidelines, including: Haloacetic acids (HAA9), Haloacetic acids (HAA5), Total trihalomethanes (TTHMs), Trichloroacetic acid, Bromodichloromethane, Chloroform, Dichloroacetic acid, Chromium (hexavalent), Dibromochloromethane, Perfluorooctanoic acid (PFOA), Nitrate and nitrite, Nitrate, Radium, combined (-226 and -228), Perfluorooctane sulfonate (PFOS), Dibromoacetic acid. For most residents, a properly certified home filter at the kitchen tap is the most cost-effective way to reduce exposure to whatever's in your water. See our filter recommendations below, matched specifically to this utility's contaminant profile.
Quick actions for ANSONIA residents
Top concerns in this water
Based on the most recent EPA and EWG data, these are the most significant water quality issues for REGIONAL WATER AUTHORITY.
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.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 34.0 ppb, 567x above the EWG health guideline of 0.06 ppb.
Haloacetic acids (HAA5) significantly above health guideline
Moderate concernHaloacetic acids (HAA5) detected at 31.5 ppb, 315x above the EWG health guideline of 0.1 ppb.
Total trihalomethanes (TTHMs) significantly above health guideline
Moderate concernTotal trihalomethanes (TTHMs) detected at 39.4 ppb, 263x above the EWG health guideline of 0.15 ppb.
Contact REGIONAL WATER AUTHORITY
Reach the utility directly for service issues, water quality concerns, or to request your Consumer Confidence Report.
General Contact
Treatment Plant
Recommended water filters for ANSONIA
Filters matched to the specific contaminants in this water supply.
Reverse Osmosis or NSF P473 certified carbon
$80-$750Activated carbon and RO are the only technologies proven to remove PFAS at certified levels.
Carbon block (NSF/ANSI 42 + 53)
$40-$750Activated carbon is highly effective for disinfection byproducts like TTHM and HAA5.
Disclosure: TapWaterSafety earns a commission from purchases made through these links. This does not influence our scoring methodology or filter selection.
Score breakdown
This utility's overall score of 55/100 breaks down across five weighted components. Read the full methodology →
Contaminants detected — international standards comparison
Every contaminant detected, compared side-by-side against US EPA legal limits, the EU Drinking Water Directive (2020/2184), WHO Guidelines, and California's Public Health Goal (the strictest US benchmark). 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 |
34.0 ppb | 0.06 | — | — | — | — | — | 567× over |
| Haloacetic acids (HAA5) Disinfection byproduct |
31.5 ppb | 0.1 | 60.0 | 60 | — | — | — | 315× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
39.4 ppb | 0.15 | 80.0 | 100 | — | — | — | 263× over |
| Trichloroacetic acid Disinfection byproduct |
17.1 ppb | 0.1 | — | — | — | — | — | 171× over |
| Bromodichloromethane Disinfection byproduct |
5.17 ppb | 0.06 | — | — | — | — | — | 86× over |
| Chloroform Disinfection byproduct |
24.3 ppb | 0.4 | — | — | — | — | — | 61× over |
| Dichloroacetic acid Disinfection byproduct |
11.0 ppb | 0.2 | — | — | — | — | — | 55× over |
| Chromium (hexavalent) Heavy metal |
0.237 ppb | 0.02 | — | — | — | — | — | 12× over |
| Dibromochloromethane Disinfection byproduct |
0.851 ppb | 0.1 | — | — | — | — | — | 8.5× over |
| Perfluorooctanoic acid (PFOA) PFAS |
0.763 ppt | 0.09 | 4.0 | 100 | 100 | 0.007 | — | 8.5× over |
| Nitrate and nitrite Inorganic |
0.94 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 6.7× over |
| Nitrate Inorganic |
0.913 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 6.5× over |
| Radium, combined (-226 and -228) Radiological |
0.28 pCi/L | 0.05 | 5.0 | — | — | — | — | 5.5× over |
| Perfluorooctane sulfonate (PFOS) PFAS |
1.32 ppt | 0.3 | 4.0 | 100 | 100 | 1 | — | 4.4× over |
| Dibromoacetic acid Disinfection byproduct |
0.0719 ppb | 0.03 | — | — | — | — | — | 2.4× over |
| Manganese Heavy metal |
93.7 ppb | 100.0 | — | 50 | 80 | — | — | Fails EU |
| Uranium Radiological |
0.4 pCi/L | 0.43 | 20.0 | 30 | 30 | 0.43 | — | Below guideline |
| Chlorate Disinfection byproduct |
177.5 ppb | 210.0 | — | — | — | — | — | Below guideline |
| Barium Heavy metal |
82.7 ppb | 700.0 | 2000.0 | — | 1300 | 2000 | — | Below guideline |
| Monochloroacetic acid Disinfection byproduct |
2.71 ppb | 53.0 | — | — | — | — | — | Below guideline |
| Di(2-ethylhexyl) phthalate Semi-volatile organic compound |
0.146 ppb | 3.0 | 6.0 | — | — | — | — | Below guideline |
| Vanadium Other |
0.657 ppb | 21.0 | — | — | — | — | — | Below guideline |
| 1,4-Dioxane Semi-volatile organic compound |
0.0104 ppb | 0.35 | — | — | 50 | 1 | — | Below guideline |
| Monobromoacetic acid Disinfection byproduct |
0.468 ppb | 25.0 | — | — | — | — | — | Below guideline |
| Bromoform Disinfection byproduct |
0.00402 ppb | 0.5 | — | — | — | — | — | Below guideline |
| Perfluorobutane sulfonate (PFBS) PFAS |
0.337 ppt | 2000.0 | — | — | — | — | — | Below guideline |
| Perfluoropentanoic Acid (PFPeA) PFAS |
0.103 ppt | 1000.0 | — | — | — | — | — | Below guideline |
| Strontium Radiological |
0.0638 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| Bromide Other |
26.3 ppb | — | — | — | — | — | — | Below guideline |
| Chromium (total) Heavy metal |
0.123 ppb | — | 100.0 | — | — | — | — | Below guideline |
| Fluoride Inorganic |
0.527 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 (4th ed.), California OEHHA PHGs, EWG Tap Water Database.
REGIONAL WATER AUTHORITY service area
This water system serves 20 communities in New Haven County, Connecticut. Click any city for its dedicated tap water quality page.
Find the right filter for ANSONIA water
Browse filter categories by water-quality concern. Each option below is NSF-certified for the matched contaminant type.