The Hillview Reservoir is a 164 acres (0.66 km2) storage reservoir in southeastern Yonkers, New York. It was built within a six-year period from 1909-1915 by the New York City Board of Water Supply to receive water from the newly constructed Catskill Aqueduct, which drained water from the Ashokan Reservoir, and sent it down into the Kensico Reservoir, where it would, in turn, be drained back into the Catskill Aqueduct, and sent into the Hillview Reservoir. Frank E. Winsor was the engineer in charge of construction of both Hillview and Kensico as well as 32 miles (51 km) of the Catskill Aqueduct.
The reservoir itself has a maximum capacity of 900 million US gallons (3,400,000 m³), and water from the reservoir is sent through New York City Water Tunnels No. 1 and No. 2. New York City Water Tunnel No. 3, which is still under construction, is planned to take water from the Kensico Reservoir, and immediately send it into the Hillview Reservoir, and then into the rest of New York City. The reservoir itself does not impound a river, and is held up by walls on all sides.