One of five Dedham-Westwood Water District wells tested positive for E. coli bacteria, a so-called fecal indicator, but district officials said the well was taken offline.
“This is not an emergency,” district officials said in a statement Friday. “You do not need to boil your water or take other corrective actions at this time.”
The water system was notified Wednesday that an untreated water sample from Well 3A, collected on Tuesday, tested positive for E. coli, according to the statement.
Fecal indicators, including E. coli, are used to detect ground water sources that may be susceptible to fecal contamination, which may contain harmful viruses or bacteria, according to the statement.
“Fecal indicators are microbes whose presence indicates that the water may be contaminated with human or animal wastes,” the statement read. “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.”
The well was taken offline as soon as the district was made aware of the positive sample.
Water delivered to taps served by the Dedham-Westwood Water District is treated with chlorine to kill viruses and bacteria, and no treated samples collected in the distribution system contained any fecal contaminants.
However, the chlorine disinfection system in the Dedham-Westwood wells has not been certified by Massachusetts Department of Environmental Protection to kill 99.99 percent of viruses, according to the statement.
Five repeat samples were collected from Well 3A on Wednesday, and were negative for total coliform and E. coli.
The water district will be conducting additional sampling to evaluate potential contamination and will take further action as necessary, according to the statement.