N.Y. Real Prop. Tax Law § 410-a

§ 410-a. Special districts. Real property owned by a special\ndistrict, or the property owners therein, not within its district\nboundaries which is used as a sewage disposal plant or system, including\nnecessary connections and appurtenances, or real property owned by a\nspecial district used as a water plant, pumping station, water treatment\nplant, or reservoir, including necessary connections and appurtenances,\nshall be wholly or partially exempt from taxation and exempt from\nspecial ad valorem levies and special assessments to the extent provided\nin section four hundred ninety of this chapter, by any municipal\ncorporation in which located, providing the governing board thereof\nshall so agree in writing.\n