An urgent notice was posted on greenlawnwater.org's website urging all residents in the Greenlawn Water District to boil their water before using.
Positive samples of bacteria were found during a routine check, the district said.
Chlorine has been added to the water by the district as a precautionary measure.
Here is a copy of the email received by Commack School District residents
The Greenlawn Water District has started emergency chlorination of the water system due to positive samples for bacteria detected during routine weekly monitoring and at one of its supply wells. The chlorine is being added as a precautionary measure.
Please check the water district's website at www.greenlawnwater.org for updates on this situation, or call (631) 261-0874 if you have any questions.