The Springhead is at the end of the lake close to the Hermitage, and as well as the visible entrance tunnel there are a complex of tunnels. Known as the Conduits they pass under the south lawn of the house and are the water source for the lake, and at present, the most westerly rising of the River Wandle when the water table is high enough.
The Springhead / Conduits have been built in a number of phases, the earliest being likely to be before 1700.
In early 2015 the main restoration was carried out on the external façade and the entry tunnel, and included a new entry gate more sympathetic to the tunnel shape. Restoration was funded by donations and money from the Trust.