J Murphy has been picked by United Utilities to refurbish the Haweswater Aqueduct tunnels and conduits in north-west England.
The aqueduct is 90km long, over 100m deep in places, and connects water supplies in Cumbria with Manchester.
Murphy has been awarded the design and construction contract after United Utilities spent £22m on a detailed structural analysis of the pipe.
The survey involved draining and shutting down the system to allow maintenance crews inside and involved over 400 workers.
The Haweswater Aqueduct took over 20 years to build and was commissioned in 1955 by the Manchester Corporation, forerunner of the city council.
The ‘mega-pipe’ provides the water supply for 2 million people across Greater Manchester, allowing 570 million litres of water to flow to the city every day.