JONESBOROUGH, Tenn. (WJHL) — The Town of Jonesborough’s water department is conducting extra flushing of waterlines in an area that recently tested over federal guidelines for compounds called trihalomethanes.

The town’s utility manager also said Jonesborough plans to install a pump station in the area “to increase flow and pressure to the area so that town personnel can flush that area more aggressively.”

Customers who receive water in the Glendale Road area — about 120 in all according to Jonesborough Utility Manager Kevin Brobeck — recently received letters about the testing for the July-September quarter exceeding the federal “maximum contamination level” for total trihalomethanes.

The amount was barely over the federal maximum of 0.080 milligrams per liter — with a reading of 0.08073 milligrams per liter. Brobeck referenced it in an email to News Channel 11 as less than one part per billion.

Customers, who represent less than 1% of the utility’s 13,000 total water customers, received letters dated Nov. 16. Those letters stated that the water is safe to drink.

Trihalomethanes typically result when chlorine reacts with natural organic matter in the water the chlorine is disinfecting.

The letter to customers states the utility will balance efforts to flush the lines more frequently “without increasing the microbial risks” associated with having less chlorine disinfecting the water.

Brobeck said the current “aggressive flushing” of the site by town personnel will continue until the pump station is installed. Jonesborough is in the planning and design phase for that equipment and doesn’t yet know how much it will cost.

The letter to customers says once installed it will “enhance our flushing system and reduce the age of water in the system.”

Records from the Tennessee Department of Environment and Conservation (TDEC) show this is the fourth time in the past eight years the site has tested over the federal limit for trihalomethanes.

Each of the other tests — in the first quarter of 2017 and the first and second quarters of 2015 — showed higher levels than the most recent one. They ranged from 0.0812 milligrams per liter (2017) to a high of 0.085 milligrams per liter.

“We take great pride in distributing clean potable water to all of our customers and will continue to do so in the future,” Brobeck wrote.