WINCHESTER — The city has received the Water Fluoridation Quality Award from the U.S. Department of Health (DOH) and Human Services and the Centers for Disease Control and Prevention (CDC).

This is the third consecutive year the city has received the designation, according to a recent news release. It indicates that the local water is treated efficiently and expertly at the Percy D. Miller Water Treatment Plant, located on Route 840 near Middletown.

“They’re doing a really good job of adding fluoride to their water,” said Jim Moore, field officer for the DOH Office of Drinking Water in Lexington. “One of the important things is making sure fluoride is dosed appropriately.”

Too little fluoride isn’t enough to prevent tooth decay, according to information from the CDC. But, too much fluoride, especially over a long period of time and in children younger than 8 years old, can cause dental fluorosis — which stains and wears tooth enamel. Almost all water contains some naturally occurring fluoride.

A city news release from communications manager Amy Simmons states that the “[DOH] recommends a level of 0.7 milligrams per liter (mg/L) of fluoride in drinking water,” which the city maintains to prevent and control tooth decay.

Moore said to make sure the right amount of fluoride is added, testing is conducted at the Middletown treatment plant every day. Then, once a month, a sample is sent to a state lab to make sure readings are accurate.

“The results they get are truly what the dosage is,” said Moore, noting that his office oversees 547 water systems in an area from Roanoke to Winchester, and as far east as Charlottesville.

The city’s water comes from the North Fork of the Shenandoah River, according to city information. The release states that the water is treated and supplied to approximately 11,000 accounts — all city and some Frederick County customers. The water treatment plant can provide up to 10 million gallons of water per day.