Physical & aggregate
TOC in U.S. tap water
211 public water systems across 38 U.S. states report TOC in their annual Consumer Confidence Report. 5 sit at or above the federal limit.
What it is
Total organic carbon — a measure of organic material dissolved in the water.
Why it's regulated
Not harmful itself, but it is the raw material that forms disinfection byproducts; removal is a treatment requirement.
At or above the federal limit (5)
| Water system | Measured | vs. limit |
|---|---|---|
| Kansas City, KS 2024 annual report | 2.8 mg/L | 9.3× the limit |
| Centennial, CO 2023 annual report | 2.31 | 2.3× the limit |
| Gilbert, AZ 2024 annual report | 19.03 % | 1.3× the limit |
| Pueblo, CO 2023 annual report | 1.16 | 1.2× the limit |
| Albuquerque, NM 2024 annual report | 1.1 | 1.1× the limit |
Within the federal limit (3)
| Water system | Measured |
|---|---|
| Overland Park, KS 2023 annual report | 3 |
| Dallas, TX 2024 annual report | 3.27 mg/L |
| Broken Arrow, OK 2024 annual report | 1.12 mg/L |
Frequently asked
+What is TOC?
Total organic carbon — a measure of organic material dissolved in the water. Not harmful itself, but it is the raw material that forms disinfection byproducts; removal is a treatment requirement.
+What is the federal limit for TOC in drinking water?
The federal MCL for TOC is 1 . 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 TOC over the federal limit?
5 of the 211 public water systems on The Water Map report TOC at or above its federal limit, spanning 38 U.S. states. The full list is on this page.
+How can I check if TOC 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 TOC.