BOSTON -- Spencer town officials ordered residents not to use water Wednesday after almost 90 people were treated for burns and irritation from too much sodium hydroxide in the water supply, the state Department of Environmental Protection said.

"They are in a variety of stages in the decontamination process. The majority of the cases are in the mild category," Spencer Town Manager Carter Terenzini said.

Officials said about 6,000 residents were affected by the order and crews went door to door to advise residents about the ban. Eighty-six Spencer residents, including 12 children, needed to be treated at the hospital or at decontamination tents on Wednesday.

"It is a serious situation. We obviously suggest that people make sure that they don't use this water for drinking, cooking or bathing until further notice," said Ed Colletta of the Department of Environmental Protection.

Schools remained open on Wednesday, but restaurants in the community were ordered to close. Taverns, bars and grocery stores stayed open, but they were ordered to not have contact with the town water supply.

Officials also told residents to throw out any ice cubes, juice or baby formula that may have been made with the water. Residents were able to pick up bottled water at the Spencer Town Hall.

Officials said a system malfunction caused an "overfeed" of sodium hydroxide into an automated system at the Meadow Street water treatment plant sometime overnight.

"It is a buffering agent that raises the pH, and it's normally put into the system. Unfortunately, the chemical feed pump malfunctioned and too much got inserted," said Spencer Superintendent of Utilities Margaret Bacon.

"We will be asking for an independent investigation of what happened," Terenzini said.

Shannon Sweeney said her husband, Michael, became nauseated after drinking water Wednesday morning.

"I went to check on him, he had a fever, he was nauseous, vomiting. He was really sick, so we called the fire department and they came down," she said.

Sweeney said her husband and two neighbors had to be taken for treatment.

"He wasn't burned -- he was just really nauseous and sick, chills, really bad chills. He drank water earlier this morning, he had two full glasses," she said.

"My understanding is that it does cause light burning or skin irritation, and anybody who does come in contact with the water should use bottled water to wash it off and call for medical help immediately, and then they can be taken care of for that," Colletta said.

The town was flushing the entire water system out by opening hydrants.

"The do-not-use order will be in effect at least through (Wednesday), and we'll continue to monitor it with the assessment of the town to determine what's next and let people know from there," Colletta said.

The system flushing could be complete Wednesday afternoon, but residents may not be able to use the water until end of business on Thursday. The town will also have an independent lab test the water system.

"It is disruptive because many people don't understand and many think this has to do with terror, and this is not the case at all. Not the case," said Sandra Krasnecky who works at Dienes Corp. in Spencer.