Due to a failed safeguard, too much fluoride entered the city of Kalamazoo’s water system that supplies parts of Texas Township in January, according to a news release from the city.

The higher concentration of fluoride entered the city’s system within a three-hour time frame Jan. 15, and city staff corrected the problem Jan. 16, said Sue Foune, the city’s deputy public service director. A check valve had failed in the chemical feed system.

Tests within the distribution area showed the fluoride level at 2.05 parts per million, and and after hydrants were flushed results ranged from 0.85 to 1.20 parts per million, Foune said. The secondary health standard for fluoride is 2 parts per million.

The fluoride chemical mixes with thousands of gallons of water before entering the water distribution system, and the pure chemical did not enter the distribution system connected to the city’s water customer service lines, Foune said.

The city of Kalamazoo’s water is treated with fluoride to help prevent tooth decay. The U.S. Environmental Protection Agency’s maximum contaminate level for fluoride is 4 parts per million. Concentrations that exceed 2 parts per million can cause fluorosis, a cosmetic dental problem that affects young children. Water samples collected after the Jan. 15 incident showed concentrations that exceeded 2 parts per million, but did not exceed 4 parts per million.

Foune said the city is required to report such incidents, and has one year from the date of the incident to do so.

Emily Monacelli is a government and taxes reporter for the Kalamazoo Gazette.