CLIFTON – The City’s well remains closed and will undergo ultraviolet light treatment after testing positive for total coliform bacteria.

The City shut down the public water source last month after one out of five samples taken by the Passaic Valley Water Commission showed the presence of the bacteria. City Health Officer John Biegel said the source of the contamination has still not been determined.

Total coliform consists of a group of microorganisms that live in the intestines of most humans and animals as well as on plants and soil and is normally passed to wells from contact with outer surfaces, including groundwater that contains the bacteria.

The microbes are generally harmless and do not cause illness, according to the Center for Disease Control and Prevention, however can pose a risk to individuals with weaker immune systems. The presence of the bacteria could also indicate the likelihood of other types of bacteria in the water including E.coli, a microorganism present in human and animal waste and can cause flu-like symptoms.

Biegel said tests showed no sign of E.coli bacteria in well.

The City is in the process of collecting bids for an ultraviolet disinfecting system that uses UV rays to kill bacteria in drinking water, Biegel said, adding that the well would re-open to the public after being treated and subsequent testing confirmed the bacteria were gone. The Passaic County Health Department must also approve the results.

"It’s really water quality at this point," he said.

The state Department of Environmental Protection requires the well to be tested quarterly and the well has had a streak of positive tests for several years, Biegel said.