is a reservoir
, five miles (8 km) south of Penicuik
. It is the largest area of freshwater
in the Lothians.
The reservoir in the Moorfoot Hills is one of a group of reservoirs which supply Edinburgh with water. It is fed by the River South Esk.
Gladhouse Reservoir is also a Site of Special Scientific Interest or SSSI, and a Special Protection Area. It is an important roosting site for Anser brachyrhynchus, the Pink-footed Goose.
There are three islands in the reservoir.