The Mottram Tunnel (Mottram in Longdendale) is a tunnel carrying drinking water by gravity from Arnfield Reservoir, Tintwistle, Derbyshire in the valley of the River Etherow, to Godley, Greater Manchester in the valley of the River Tame. It was essential to the construction of the Longdendale Chain of reservoirs constructed by John Frederick Bateman. The tunnel was built between August 1848 and October 1850, and the Godley service reservoir was built to receive and filter the water.