Gloucester's drinking water this year failed tests for substances other than the coliform bacteria that caused a boil water order this summer, according to the state Department of Environmental Protection.

The newly identified substances, total trihalomethanes, are not necessarily harmful and are not triggering a new water emergency, the city said yesterday in a series of statements issued by Mayor Carolyn Kirk.

"You do not need to use an alternative water supply such as bottled water," reads a letter being sent to residents by the city. "This is not an emergency, nor is there an imminent risk."

Trihalomethanes are a byproduct of the drinking water disinfectant process. They are substances created when excess chlorine intended to kill bacteria combines with suspended solids — like the ones that shut down the Babson water plant in August.

While they do not cause an imminent health threat, "some people who drink water containing trihalomethanes in excess of the maximum contaminant level over many years may experience problems with their liver, kidneys or central nervous system and may have an increased risk of getting cancer," the city notification says.

The notification does not come with any dates for when the trihalomethanes turned up in the water, only that city water exceeded the yearly limit.

However, the chain of events began when Babson failed due to murky water, followed by coliform bacteria and then supplemental chlorine being pumped into the system, the city suspects.

The announcement of further drinking water violations comes as the city is entering into a consent order with the state to perform capital improvements to the drinking water system estimated to cost $6 million.

Part of that order requires the city to upgrade the Babson water treatment plant before reactivating it again.

The city has also selected a new company to operate its drinking water system, France-based Veolia Water, which will replace United Water. United's parent company is also a French utility.

Patrick Anderson can be reached at 978-283-7000 x3455 or panderson@gloucestertimes.com