Holtsville is a hamlet and census-designated place in Suffolk County, on Long Island, in New York, United States. The population was 19,714 at the 2010 census. The hamlet is mainly in the Town of Brookhaven, while the southwestern portion is in the Town of Islip. An IRS Processing Center is located in Holtsville, along with NYPA's Richard M. Flynn Power Plant.
Save
Share
More