Physical & aggregate
Turbidity in U.S. tap water
240 public water systems across 36 U.S. states report Turbidity in their annual Consumer Confidence Report. 4 sit at or above the federal limit.
What it is
A measure of cloudiness from suspended particles in the water.
Why it's regulated
High turbidity can shelter microbes from disinfection; the EPA enforces it through a treatment-technique standard.
At or above the federal limit (4)
| Water system | Measured | vs. limit |
|---|---|---|
| Birmingham, AL 2024 annual report | 42 NTU | 140.0× the limit |
| Albuquerque, NM 2024 annual report | 0.13 | 65.0× the limit |
| Freedom District, MD 2024 annual report | 0.05–0.64 NTU | 2.1× the limit |
| Albany, NY 2024 annual report | 0.52–9.28 NTU | 1.9× the limit |
Approaching the limit (2)
| Water system | Measured | vs. limit |
|---|---|---|
| New Orleans, LA 2024 annual report | 0.03–1.44 | 1.0× the limit |
| Glendale, CA 2024 annual report | 4.6 NTU | 0.9× the limit |
Within the federal limit (100)
| Water system | Measured |
|---|---|
| Gilbert, AZ 2024 annual report | 0.237 NTU |
| Thousand Oaks, CA 2024 annual report | 0.14 NTU |
| El Monte, CA 2024 annual report | 0–1.8 mg/L |
| Portland, OR 2024 annual report | 0.22–1.65 NTU |
| Glendale, AZ 2024 annual report | 0.305 NTU |
| Mesa, AZ 2024 annual report | 0.3 NTU |
| Scottsdale, AZ 2024 annual report | 0.3 NTU |
| Pomona, CA 2024 annual report | 0–1.3 NTU |
| St George, UT 2024 annual report | 1.3 NTU |
| Inglewood, CA 2023 annual report | 1.1 NTU |
| Round Rock, TX 2024 annual report | 0.065 NTU |
| Torrance, CA 2024 annual report | 0.1–0.9 NTU |
| Brownsville, TX 2024 annual report | 0.05 |
| Ontario, CA 2024 annual report | 0.73 NTU |
| Tracy, CA 2024 annual report | 0.73 NTU |
| Evansville, IN 2024 annual report | 0.04 NTU |
| Carmel, IN 2024 annual report | 12 NTU |
| West Covina, CA 2024 annual report | 0.58 NTU |
| Salinas, CA 2024 annual report | 0.45 NTU |
| Hartford, CT 2024 annual report | 0.08 NTU |
| West Valley City, UT 2024 annual report | 0.4 NTU |
| Victorville, CA 2024 annual report | 0.31 NTU |
| City of Cumberland, MD 2024 annual report | 0.06 NTU |
| Eastern Region Allegany Distrib System, MD 2024 annual report | 0.02–0.06 NTU |
| Pasadena, CA 2023 annual report | 0.3 NTU |
| Visalia, CA 2024 annual report | 0.29 NTU |
| Chico, CA 2024 annual report | 0.21 NTU |
| Daly City, CA 2024 annual report | 0.2 NTU |
| Hayward, CA 2024 annual report | 0.2 NTU |
| San Francisco SFPUC, CA 2023 annual report | 0.2 NTU |
| Hesperia, CA 2024 annual report | 0.17 NTU |
| Tacoma, WA 2024 annual report | 0.015–0.034 |
| Bridgeport, CT 2024 annual report | 0.15 NTU |
| Burbank, CA 2024 annual report | 0–0.15 NTU |
| Huntington Beach, CA 2025 annual report | 0.14 NTU |
| Stamford, CT 2024 annual report | 0.14 NTU |
| Fullerton, CA 2024 annual report | 0.13 NTU |
| Costa Mesa, CA 2024 annual report | 0.12 NTU |
| Irvine, CA 2023 annual report | 0.12 NTU |
| Vallejo, CA 2024 annual report | 0.12 NTU |
| Fairfield, CA 2024 annual report | 0.11 |
| Alameda, CA 2024 annual report | 0.02 NTU |
| Albany, CA 2024 annual report | 0.02 NTU |
| Berkeley, CA 2024 annual report | 0.02 NTU |
| Castro Valley, CA 2024 annual report | 0.02 NTU |
| Crockett, CA 2024 annual report | 0.02 NTU |
| El Cerrito, CA 2024 annual report | 0.02 NTU |
| El Sobrante, CA 2024 annual report | 0.02 NTU |
| Emeryville, CA 2024 annual report | 0.02 NTU |
| Hayward, CA 2024 annual report | 0.02 NTU |
Showing 50 of 100. The full list is in the JSON API.
Frequently asked
+What is Turbidity?
A measure of cloudiness from suspended particles in the water. High turbidity can shelter microbes from disinfection; the EPA enforces it through a treatment-technique standard.
+What is the federal limit for Turbidity in drinking water?
The federal MCL for Turbidity is 1 NTU. The EPA enforces this against the regulated reporting statistic (typically a running annual average or 90th percentile), not a single-sample spike.
+How many U.S. water systems have Turbidity over the federal limit?
4 of the 240 public water systems on The Water Map report Turbidity at or above its federal limit, spanning 36 U.S. states. The full list is on this page.
+How can I check if Turbidity is in my city's tap water?
Search your city on The Water Map (https://www.thewatermap.com/) or browse the list on this page. Every U.S. public water utility is required to publish an annual Consumer Confidence Report that lists every contaminant it measured, including Turbidity.