NEW YORK (CBS 2) — A boil water advisory is in effect for several suburban New York communities on both sides of the Hudson River.

The advisory is in effect for sections of Ramapo and New City in Rockland County until Monday night pending results of two tests. About 540 United Water customers are affected.

In Westchester County, residents in Sleepy Hollow, Tarrytown, Elmsford, Hawthorne, Valhalla and Thornwood are also advised to boil water before drinking or using it for food preparation.

The advisory was lifted Monday for residents of Briarcliff, Grasslands Reservation and Irvington.

Health officials say the recent snowstorms may have affected water quality there.

The advisory means water should be boiled at least one minute.