REGIONAL – After detecting coliform bacteria in the water supply at two of its schools, ISD 2142 will take steps to better purify water for drinking. Coliform bacteria are commonly used as an indicator of the sanitary quality of foods and water.

In the meantime, the district has taken precautions, providing bottled drinking water for students and staff and placing warnings on water fountains and other taps not to drink the water at both the North Woods and South Ridge schools.

Both schools have independent water systems that draw water from wells on their sites. Tests indicated there was no problem with the source water, said ISD 2142 Maintenance Director Tom Cundy. Instead the problem lies in the water storage tanks.

Water usage at the school has been averaging about 2,000 gallons a day, far below expectations. That allows water to sit in the tank for lengthy periods, allowing bacteria to breed.

“We’re not turning over the water supply in the tank fast enough,” said Cundy, who said the tanks hold 30,000 gallons. The tanks had to be that large to meet state requirements for fire suppression.

Cundy said the district will add chlorine to the tank water to prevent future incidents He is researching different options, but said the chlorine could be introduced into the water supply through a pump installed in the tank.

Stew Thornley, of the Department of Health, said the district is following proper protocols and going beyond that to ensure that the drinking water is safe.

“Coliform itself is not harmful, but it indicates the possibility of other bacteria that could cause illness in the water supply,” said Thornley. “We like to err on the side of caution when it comes to drinking water.”

Thornley said it’s not unusual not to include chlorination in a small water distribution system such as at the schools and said the water tanks and plants met all its standards for construction.

The low water usage is likely to blame for the problem, he said, and probably contributed to problems in the water supply at the schools earlier this year. Adding chlorine to the mix should address the issue.

Adding chlorine raises the possibility of other unwelcome byproducts, Thornley acknowledged. But the risks are not as urgent as bacteria that can cause immediate illness. For instance, he said chlorine at elevated levels over a lifetime of exposure has been found to lead to a higher risk of cancer.

Cundy doesn’t anticipate it will require high levels of chlorine to sanitize the water supply. And he expects the bacteria, which thrive in heat, to become less of an issue as the temperatures fall.

“In the summer and spring, we’re running our sprinklers so that helps roll the water over in the tank more frequently,” he added.

Meanwhile, the water system will be shocked and flushed to remove any traces of harmful bacteria and then retested before it’s deemed safe to drink again. Cundy expects that process to be completed next week.

In the interim, the district plans to conduct weekly tests of the water supply to ensure it stays safe to drink.

That’s beyond what the Department of Health requires, according to Thornley, who said the department will require monthly tests of the water supply.

“The district is doing all it can to ensure the water supply will be safe,” said Thornly. “They’re willing to make the investments to ensure the water supply is safe and they’re following up with testing.”