A method for installing at least one cable, or in the removal of at least one cable from a tube in which is already present at least one other cable.

A Y-piece is attached to the end of the duct (2), one branch of which allows the pre-installed cable (3) to exit through a seal. The other branch is linked by a waterproof pipe (7) to an installation unit (5). The cable (1) which is to be installed passes through the unit (5) and into the duct (2). A pressurized water supply is coupled (6) to the unit. The flow of water forces the new cable through the duct.