Pump device (12) for pumping a substance, containing a tubular body (19) with an insertion opening (25) on which can be mounted a semi-submersible pump (13), which is formed of a non-submersible portion (14) consisting of a housing (15) in which is provided a drive (16) and a submersible portion (17) containing a rotatable shaft (18) which can be coupled to the drive (16) and whereby, in the mounted condition of the pump (13) on the tubular body (19,) the submersible portion (17) is provided through the insertion opening (25), and whereby the drive (16) can operate bidirectionally so as to move a substance in the tubular body (19) from a first open end (21) to a second open end (22), and vice versa.
