For over a week, some residents of northern and central parts of Jersey have been experiencing a foul taste and smell coming from their drinking water.

On Monday, the New Jersey Department of Environmental Protection said the changes in the odor and taste of the drinking water are due to a leak from a repackaging facility in Branchburg. The facility repackages fragrances, essential oils and flavorings.

“Since Tuesday, Dec. 17, our teams have worked tirelessly, collecting hundreds of water quality samples around the clock throughout our system to help address the cause of the changes in taste and odor,” said Mark McDonough, president of New Jersey American Water, the water provider in the region. “Our proactive measures to adjust our treatment process and flush our system have allowed us to continue to provide water to our customers that meets state and federal drinking water quality standards, despite these challenges.”

According to the DEP, the material in the spill consisted of compounds — most notably alpha-pinene — which are commonly used as fragrance and food additives. Due to the fragrant nature of the compound, it can be smelled at minute concentrations measured in parts per trillion.