East Warwick Reservoir is located in the London Borough of Waltham Forest at Walthamstow.

The storage reservoir is part of the Lee Valley Reservoir Chain and supplies drinking water to London.

[1] The reservoir is owned by Thames Water.

The reservoir was constructed on marshland in the mid–19th century by the East London Waterworks Company.

[3] The reservoir is popular with birdwatchers, naturalists and anglers, but access is by permit only.