A raw, untreated water sample collected from one of the town’s seven pumping stations two months ago tested positive for the E. coli bacteria, officials said last week. Water Division Operations Manager John J. Marsh posted a public notice assuring residents the townwide water system routinely monitors the presence of drinking water contaminants, and monitoring on June 11 showed that a sample collected a month prior on May 10 was contaminated, he said. “During normal operations, raw water from our wells is pumped from the ground and is disinfected with chlorine to kill viruses and fecal indicators including E. coli,’’ Marsh said in his statement. “The chlorinated water is delivered to you. None of our treated water system samples tested positive for any bacteria.” Pumping Station No. 2 has been taken offline and tests are being conducted on additional samples until it can be certified that E. coli is no longer present in raw samples, he said.