The well water supply at a southern Maine middle school recently tested positive for elevated levels of E. coli bacteria, prompting school officials to issue warnings to keep students and staff from drinking the water.

The drinking water ban at Marshwood Middle School in Eliot will be in place for at least three more weeks and will be lifted only after successful follow-up testing.

There have been no reports yet of sickness at the school, which serves approximately 500 students from Eliot and South Berwick and is part of RSU 35.

Principal John Caverly first notified parents on Sunday that water tests at the school turned up positive for Escherichia coli, or E.coli, according to emails sent to parents.

In another email to parents on Monday, Caverly wrote that he and other school staff had coordinated with state officials to issue a boil water order. He also said the school ordered bottled water and encouraged parents to send a filled water bottle to school with their children.

Food service workers have been boiling any water used for cooking but officials said the water remains suitable for students and staff to use for washing hands.

Caverly wrote on Monday that the contamination was believed to have occurred when a valve to an underground storage tank was left open. The valve was used to supply water to irrigate athletic fields but is no longer in use, he said.

In a third email to parents on Tuesday, Caverly wrote that a field inspector from the Maine Center for Disease Control inspected the school’s well and agreed that the contamination was likely caused by the open valve.

In addition to capping the valve, school officials have flushed the well and have installed a chlorine treatment system.

E. coli is most commonly linked to undercooked ground beef, but the bacteria can find its way into water supplies through fecal matter, either from humans or animals, according to the Environmental Protection Agency.

Those exposed to E. coli can become violently sick, particularly children and the elderly.

“The nurse is very aware of the situation and is keeping an eye on any signs,” said Mary Nash, the district’s superintendent. “Everybody has been really understanding and supportive.”

John Martins, spokesman for the Maine CDC, said the department’s drinking water program receives between 6 and 10 reports of E. coli in water every year. Postive tests must be reported to the state within 24 hours.

Nash said the school has never seen elevated levels of E. coli bacteria before and last had water issues back in 2002.

Tests are conducted quarterly, which means the last test was conducted approximately three months ago. Nash said officials don’t know when the system might have been contaminated but he said, until the last month or so, there was snow covering the valve.

Larger water systems that serve thousands of people or more are subject to more frequent testing, according to the Safe Drinking Water Act, but there are different standards for wells.

The most significant case of E. coli contamination in water occurred in 2000 a small community in Ontario, Canada. Seven people died and thousands got sick.

Last year, E. coli was found in the water system in Mercer Island, near Seattle, prompting citywide boil water orders and forcing many restaurants to close. Officials were never able to determine what caused the contamination, according to press reports.

Staff Writer Eric Russell can be contacted at 791-6344 or:

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Twitter: @PPHEricRussell

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