Abberton Reservoir is an artificial body of water located close to the coast of Essex in the east of England. It is 5 miles (8 km) south-west of Colchester near the village of Layer de la Haye. Its geographical coordinates are 51°49.2'N 00°51.6'E? / ?51.82°N 0.86°E? / 51.82; 0.86 (grid reference TL976182).
It is a large, shallow, freshwater storage reservoir and is the largest freshwater body in Essex. The reservoir contains around 25,000 Megalitres. It is a pumped storage reservoir. This means water is pumped from the rivers Chelmer, Blackwater and Stour to fill it, rather than simply relying on rainfall in the limited catchment area. The reservoir was formed by damming a shallow river valley. There a plans to increase the capacity of Abberton reservoir to 40,000 megalitres by raising the bank height all the way round.
On its margins are found well-established plant communities that provide important opportunities for feeding, nesting and shelter. Abberton Reservoir is important as an autumn arrival area for waterbirds that then spend the winter elsewhere.