Metals
Calcium in U.S. tap water
392 public water systems across 21 U.S. states report Calcium in their annual Consumer Confidence Report. None currently sit at or above the federal limit.
What it is
A naturally occurring mineral that contributes to water hardness.
Why it's regulated
Not federally regulated for health; affects scaling and taste.
Calcium by state
Every state where a public water system reports Calcium in its annual report, ranked by systems at or above the federal limit.
Frequently asked
+What is Calcium?
A naturally occurring mineral that contributes to water hardness. Not federally regulated for health; affects scaling and taste.
+What is the federal limit for Calcium in drinking water?
The federal NL for Calcium is 500 mg/L. 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 Calcium over the federal limit?
Zero of the 392 public water systems in The Water Map dataset currently report Calcium at or above its federal limit.
+Which states report the most Calcium in their drinking water?
No state currently has a system reporting Calcium at or above its federal limit in The Water Map dataset. California, Wisconsin, Tennessee have the most systems measuring it.
+How can I check if Calcium 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 Calcium.