Chestnut Hill Reservoir is a reservoir created in 1870 on existing marshes and meadowland to supplement the city of Boston's water needs. It is surrounded by Chestnut Hill, a neighborhood which consists of parts of Boston, Brookline, and Newton. The reservoir, though, is located entirely within the city limits of Boston It is recognized today on the National Register of Historic Places and it has designation as a City of Boston Landmark.
On May 1, 2010, the Chestnut Hill Reservoir was temporarily brought back online during a failure of a connecting pipe at the end of the MetroWest Water Supply Tunnel. Though a boil-water order was issued for fear that the water would not be safe to drink, following heavy treatment with chlorine later tests showed the water to be completely safe for drinking.