Selbyville water back to safe TTHM levels, according to tests

Selbyville is getting back to normal after a water violation earlier this year. Drinking water tested at south Main Street showed decreasing levels of a disinfection byproduct called Total Trihalomethanes (TTHMs).

In May, Delaware Division of Public Health announced that the Town of Selbyville’s water supply had exceeded the maximum contaminant level (MCL) at the Main Street pipe. The allowable four-quarter average of TTHM is 80 parts per billion (ppb). But this spring, the Office of Drinking Water found that Selbyville was averaging 123.8 ppb.

Selbyville responded by constant flushing of the water and more independent laboratory tests, Councilmember Rick Duncan Sr. reported over the next few months.

So on Sept. 22, TTHM measured only 71 ppb, so the average plummeted to 92.5 ppb.

These numbers are much more promising. But state tests only occur every three months, so mathematically, Selbyville’s average won’t return to official compliance for a while.

“It is encouraging that their results are improving,” stated Andrea Wojcik, Div. of Public Health’s chief of community relations. “The town has been working with the Office of Drinking Water on implementing some actions to reduce TTHMs. This includes actions such as flushing [water] mains, especially dead ends, to reduce the age of the water …”

“Total Trihalomethanes (TTHMs) are created in water systems when chlorine that is added to prevent bacterial contamination interacts with organic matter in the source water,” Wojcik stated.

Selbyville water tests are regularly performed at several locations across town. TTHMs have plagued the southern pipes before, since the water usage is lower near the dead ends. TTHMs form when disinfected water sits stagnant in the system for too long.

But ultimately, the current TTHM violation isn’t cause for alarm, according to Wojcik.

Residents were not instructed to boil their water or take other corrective actions, which has been required in a more serious water situations. TTHMs can present increased risks to infants, the elderly or those with other medical problems, so people could consult with their doctor.

“The amount of THMs formed when drinking water is disinfected is thousands of times lower than the amount that could cause severe poisoning. Some people who drink water containing trihalomethanes in excess of the MCL over many years may experience problems with their liver, kidneys, or central nervous systems, and may have an increased risk of getting cancer,” Wojcik wrote.

“Selbyville’s readings over time have not demonstrated a pattern of high levels which could lead to such health problems,” Wojcik added. “The health risks linked with THMs in water are very small, compared to the risk of potentially deadly infectious diseases in drinking water that is not disinfected.”

Residents concerned with the water supply could install extra protections, like a carbon filtration system on the faucet.

Anyone with questions can contact Selbyville Town Hall at (302) 436-8314 or Sharon Scheers, at the Office of Drinking Water at (302) 741-8627.

Water test results are online by searching “Selbyville” at The original Division of Public Health notice is online at