Mackay Estate Water Tower is a historic water tower located at East Hills in Nassau County, New York. The tower is a utilitarian structure manufactured by the Phillipsburg, New Jersey firm of Tippett and Wood. The tank is round in plan and topped by a bell-shaped slate roof and copper cupola. The tank stands on eight legs, each of which is 34 feet tall. The water tower and tank are concealed inside a tall structure designed by Stanford White that is constructed of stone, laid in random ashlar, and the roof is spanned by a Guastavino tile dome. The tower was originally a component of Clarence Mackay's Harbor Hill Estate.