or 34 o 34 ring may be provided to seal the pipe and prevent contamination to the interior if desired a seal e g a cup seal 31 fig5 can be provided at the top of the perforated pipe or screen to prevent fluid injected into the device from bypassing between the pipe and extension tube when the tube is raised with the embodiments shown in fig5 and 6 the drop pipe is not connected directly to the perforated pipe but is nonetheless in fluid communicating relationship with the perforated pipe a variation of the embodiment of fig1 is shown in fig8 in this embodiment a similar drive point 10b is used to which is connected a perforated pipe 20 by means of threaded tapered stub 15 and a drop pipe 22 is connected directly to the perforated pipe 20 however an elongated annular sealing body 14b replaces the extension tube 12a and the sealing collar 14a shown in fig1 and performs the function of both thus the sealing body 14b seals the device to the lateral surfaces of the borehole just as does the collar 14a since it is also sized so that none of the other components of the device have a larger outside diameter in the embodiment of fig8 an adapter 16b is connected to both the sealing body 14b and drive rod 18 as in fig1 with opposite ends reverse threaded therefore the adapter.