Bristol Water is to build a new 13.5km (8.3 mile) pipeline to improve water supplies to the north of the city. The �8m project will see a new water main run from Barrow Water Treatment Works to Hicks Gate near Keynsham.
The firm said the pipe will allow it to pump water from the works to the city in times of emergency.
Managers said the pipeline route has been discussed with local councils and conservation groups. Construction work should begin in the next month.
The 18-month project will see the pipeline cross underneath both the A37 and A38.
Bristol Water said it did not believe there would be any "unnecessary disruption" on either road.