Water samples have tested positive for coliform bacteria, but the town's drinking water is safe, said Sewer and Water Department Superintendent Rick Mattson.
Although the bacteria are natural and not necessarily dangerous, said Mattson, coliforms can be an indicator that other, potentially harmful, bacteria may be present.
In a press release, Mattson said four samples were found contaminated with the bacteria during a routine sampling on Feb. 9.
The number of positive samples exceeded the maximum level for total coliforms according to Massachusetts drinking water regulations.
"Coliforms were found in more samples than allowed and this is a warning of potential problems," Mattson wrote.
The federal Environmental Protection Agency states no more than 5 percent of samples can contain coliforms, but since Walpole collects under 40 water samples a month, they do not have to abide by that standard.
Mattson said the presence of coliforms in drinking water is generally a result of a water treatment problem or bad pipes.
The water department has resampled the locations in question and they were bacteria-free, according to Mattson. More samples have been collected and were sent to a laboratory, he said, with the department awaiting the results.
"We will continue to monitor this situation and work toward resolution," Mattson wrote.
