Physical & aggregate
pH in U.S. tap water
123 public water systems across 24 U.S. states report pH in their annual Consumer Confidence Report. 46 sit at or above the federal limit.
What it is
A measure of how acidic or basic the water is.
Why it's regulated
Regulated only as a secondary standard; very low or high pH can corrode pipes or affect taste.
At or above the federal limit (46)
| Water system | Measured | vs. limit |
|---|---|---|
| High Point, NC 2024 annual report | 6.2–9 | 1.4× the limit |
| Phoenix, AZ 2025 annual report | 6.6–8.8 | 1.4× the limit |
| Billings, MT 2024 annual report | 7.44–8.29 | 1.3× the limit |
| City of Hemet, CA 2024 annual report | 6.3–8.1 | 1.2× the limit |
| City of Menifee, CA 2024 annual report | 6.3–8.1 | 1.2× the limit |
| City of Murrieta, CA 2024 annual report | 6.3–8.1 | 1.2× the limit |
| City of Perris, CA 2024 annual report | 6.3–8.1 | 1.2× the limit |
| City of San Jacinto, CA 2024 annual report | 6.3–8.1 | 1.2× the limit |
| City of Temecula, CA 2024 annual report | 6.3–8.1 | 1.2× the limit |
| East Valley Service Area, CA 2024 annual report | 6.3–8.1 | 1.2× the limit |
| Mills Service Area, CA 2024 annual report | 6.3–8.1 | 1.2× the limit |
| Mobile, AL 2024 annual report | 8.1 | 1.2× the limit |
| Moreno Valley, CA 2024 annual report | 6.3–8.1 | 1.2× the limit |
| Salt Lake City, UT 2024 annual report | 7.1–8.1 | 1.2× the limit |
| Skinner Service Area, CA 2024 annual report | 6.3–8.1 | 1.2× the limit |
| Vancouver, WA 2024 annual report | 8.1 | 1.2× the limit |
| Manchester, NH 2024 annual report | 7.71–8.03 | 1.2× the limit |
| Columbus, OH 2025 annual report | 7.8 | 1.2× the limit |
| Fishers, IN 2024 annual report | 7.7 | 1.2× the limit |
| Green Bay, WI 2024 annual report | 7.7 | 1.2× the limit |
| Indianapolis, IN 2024 annual report | 7.7 | 1.2× the limit |
| Morgan County, IN 2024 annual report | 7.7 | 1.2× the limit |
| Westfield, IN 2024 annual report | 7.7 | 1.2× the limit |
| Carmel, IN 2024 annual report | 7.69 | 1.2× the limit |
| Allentown, PA 2024 annual report | 7.66 | 1.2× the limit |
| Suffolk, VA 2024 annual report | 7.57 | 1.2× the limit |
| Hartford, CT 2024 annual report | 7.43 | 1.2× the limit |
| Bridgeport, CT 2024 annual report | 7.4 | 1.2× the limit |
| Stamford, CT 2024 annual report | 7.4 | 1.2× the limit |
| Ventura, CA 2023 annual report | 7.5 | 1.2× the limit |
| Independence, MO 2024 annual report | 9.65 | 1.1× the limit |
| Lees Summit, MO 2025 annual report | 9.65 | 1.1× the limit |
| Overland Park, KS 2023 annual report | 9.6 | 1.1× the limit |
| Catoosa Utility District Authority, TN 2025 annual report | 7.3 | 1.1× the limit |
| Chattanooga, TN 2025 annual report | 7.3 | 1.1× the limit |
| East Ridge, TN 2025 annual report | 7.3 | 1.1× the limit |
| Elder Mountain, TN 2025 annual report | 7.3 | 1.1× the limit |
| Fort Oglethorpe, TN 2025 annual report | 7.3 | 1.1× the limit |
| Lookout Mountain, TN 2025 annual report | 7.3 | 1.1× the limit |
| Lookout Mountain, Ga, TN 2025 annual report | 7.3 | 1.1× the limit |
| Philadelphia, PA 2023 annual report | 7.1–7.3 | 1.1× the limit |
| Red Bank, TN 2025 annual report | 7.3 | 1.1× the limit |
| Rossville, TN 2025 annual report | 7.3 | 1.1× the limit |
| Signal Mountain, TN 2025 annual report | 7.3 | 1.1× the limit |
| Walker County, TN 2025 annual report | 7.3 | 1.1× the limit |
| Nashville, TN 2023 annual report | 6.91–7.21 | 1.1× the limit |
Approaching the limit (1)
| Water system | Measured | vs. limit |
|---|---|---|
| Columbia, MO 2024 annual report | 8.22 | 1.0× the limit |
Frequently asked
+What is pH?
A measure of how acidic or basic the water is. Regulated only as a secondary standard; very low or high pH can corrode pipes or affect taste.
+What is the federal limit for pH in drinking water?
The federal MCL for pH is 6.5 . 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 pH over the federal limit?
46 of the 123 public water systems on The Water Map report pH at or above its federal limit, spanning 24 U.S. states. The full list is on this page.
+How can I check if pH 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 pH.