UPDATED AS OF SEPT 10: The town is still waiting on results of the most recent tests, Dartmouth Water Department superintendent Steven Sullivan said Friday morning. The warning issued Thursday was required by the Department of Environmental Protection because E. coli was detected in some raw water samples, he said. No issues were found in treated water samples, he said. 

Residents are urged to discard ice, beverages, formula and uncooked food made from tap water collected on or before Sept. 7 after water samples from three wells have tested positive for E.coli, the Dartmouth Water Department reports.

Residents do not need to boil water.

E. coli, which is a fecal indicator, was detected in tests taken Sept. 7. The town was informed of the results Sept. 8.

Three of the 12 wells that supply drinking water to the system were affected, the department said. The wells were turned off when the positive test results were received. 

Fecal indicators are used to detect ground water sources that may be susceptible to fecal contamination, which may contain harmful viruses or bacteria. 

During normal operations, water from these wells are pumped from the ground and disinfected with chlorine to kill viruses and bacteria, including E.coli. The chlorinated water is delivered to the public.

Chlorinated water samples from the water distribution system were also collected on Sept 7. None of the chlorinated samples tested positive for E.coli. Only the untreated samples tested positive. 

The department will collect more samples, wait for the results, and inspect the water system to determine if a risk of fecal contamination exists.  Five additional samples are being collected from each of the wells affected to determine the next form of corrective action. 

“Fecal indicators are microbes whose presence indicates that the water may be contaminated with human or animal wastes,’’ the department reported. “Microbes in these wastes can cause diarrhea, cramps, nausea, headaches, or other symptoms. They may pose a special health risk for infants, young children, some of the elderly, and people with severely compromised immune systems.”

These symptoms can also be caused by issues unrelated to drinking water. Anyone with health concerns regarding these symptoms may wish to discuss their concerns with their doctor.

General guidelines on ways to lessen the risk of infection by microbes are available from the EPA Safe Drinking Water Hotline at 1-800-426-4791.