Water suppliers and municipalities that have discovered M.T.B.E . contamination in or near wells and are part of the lawsuit include the Suffolk County Water Authority , which supplies 83 percent of the county ; the Long Island Water Corporation , which supplies water to 30 Nassau communities including Baldwin , Hewlett and South Hempstead ; water districts in Franklin Square , Roslyn , Hicksville , Port Washington , Westbury , Carle Place , West Hempstead , Western Nassau and Great Neck North ; Nassau County ; and the villages of Sands Point , Mineola and Hempstead .