Caption Two tests in November showed levels at 32 parts per billion and 18 parts per billion, district officials said.
In 2001, the U.S. Environmental Protection Agency set a standard for arsenic levels in public drinking water systems at 10 parts per billion.
The district brought in bottled water stations and won’t prepare food with the well water until the issue is corrected.
The water still is safe for hand-washing, according to the district.
“We’re working diligently with our water filtration vendor and the laboratory to retest the water before it is determined that the water is safe for consumption again,” Superintendent Mike Moan said in a statement Employees from Greenwood’s water filtration vendor worked on the well system Wednesday, and a new sample was taken Thursday.
Results are expected next week, officials said.
Arsenic occurs naturally in mineral deposits in some areas of Illinois.
Groundwater that flows through those deposits can dissolve the arsenic and increase the amount of the toxin in a well, according to the Illinois Department of Public Health.
Greenwood Elementary, 4618 Greenwood Road, serves students in preschool through fifth grade.
Greenwood is the only school in the district on a well.