The water pipe will run under Croft Road to the river.
Water from the River Severn is to be used to cool the new library and history centre in Worcester, doing away with the need for air-conditioning.
A pipe will draw water from the river, which will then be used to cool other pipes that run throughout the building.
The water will then be returned to the river a little further downstream.
The Environment Agency gave permission for the scheme, provided the river temperature wasn't raised by the returning water.
The building now being constructed was designed by architects Feilden Clegg Bradley and environmental engineers Max Fordham.
Iain Paul, the design manager for the project, says they were set environmental targets, including a target of 50% renewable energy usage:
"We encouraged designers to develop ideas for harnessing the energy of the River Severn by using it for cooling the building.
"The Severn is probably the regions' largest untapped source of renewable energy."
Hot and cold
Pipes run throughout the concrete of the building
He says the building will effectively act as a storage radiator working in reverse.
It is connected to the river by two pipes running under Croft Rd and the car park.
The pipes are installed using directional drilling, which avoids the need for disruptive trench digging.
The same water-filled pipes that are used to cool the building in summer will be used to heat it in the summer, though Iain Paul says keeping it warm is less of a problem:
"Because of the large amount of heat generated by information technology, particularly in a building like ours, the energy demand from cooling is much greater than the demand for heating."