LINCOLN – A broken water main supplying the Lincoln Water District’s 3,500 customers in this Penobscot County town caused officials Tuesday to adopt emergency measures in the face of potential coliform, E. coli or other bacterial infiltration into the system.

Unprecedented in modern town history, a boil water order was issued after the break occurred in South Lincoln off U.S. Route 2 near Pollard Brook at about 9:30 a.m. Pump station workers were alerted when gauges that typically showed 900 to 1,000 gallons being pumped per minute suddenly went wild.

For the next three days, residents should use bottled water or boil town water for five minutes before drinking the water, making ice cubes, washing food, washing dishes and brushing teeth or any other activity requiring human consumption, district officials warned. Residents on well water are exempt.

“It’s only a precaution. We’re not expecting to find any problem,” water district general manager Ron Gray said Tuesday. “We have never had a break of this magnitude.”

No illnesses had been reported.

As of 6:30 p.m. Tuesday, water department workers had fixed the break and began flushing the system townwide with a double dose of chlorine, which will continue until water quality tests are performed at 8 a.m. today, Gray said. Results will be available within 24 hours.

Anyone who suffers flulike symptoms over the next few days should see a physician, Gray said. Exposure to disease-causing pathogens associated with coliform and E. coli can cause diarrhea and other gastrointestinal distress. Symptoms may take five to seven days to develop.

Residents who were buying bottled water by the jug at stores around town took the main break in stride. Many said they had tried boiling town water but stopped because it didn’t seem to help.

“What are you going to do about it? In all reality, you just have to take it day by day,” said Norman L. Adams of Lincoln, who bought six 1-gallon jugs of water and two cases of 20-ounce bottled water at Wal-Mart on West Broadway.

The line at Wal-Mart was long when Adams was there at 1 p.m., and store workers were hauling out more water for sale, he said.

At Hannaford’s, the jug water rack was empty by 5 p.m. with a sign promising more would be available at 7 a.m. today. Store employee Cyndi Towle was glad she grabbed four jugs of water for herself at lunchtime.

“I haven’t heard too much about the ban because I have been working,” Towle said.

An elderly woman stopped Towle when she saw the empty rack and the jugs Towle had in her carriage.

“Want to sell those?” the woman asked.

“Out of order” signs were springing up on water fountains around town as restaurants, such as Gillmor Farm on West Broadway, were using bottled or well water for food and dish washing. Some eateries and convenience stores, such as Why Not Stop? on West Broadway, had turned off their ice and cappuccino machines.

“After we boiled the water, I didn’t like the look of it,” said Lana Gulesian, a manager at Why Not Stop? “I just didn’t want to take any chances.”

The break spurred a blizzard of telephone calls to water district offices as customers complained or wondered why their tap water suddenly had turned brown. At their peak, calls were coming in at up to six a minute, Gray said.