14 the pump inlet screen 16 is cylindrical and may be inserted into the penetrator tube 2 of the well structure by itself without the filter pipe and may be made of stainless steel when the well is producing drinking water the segments of the helical displacement well 1 are connected together by a non rotatable coupling so that the penetrator tube 2 and the extension tubes 3 always rotate in unison for example fig4 a 4 b and 4 c illustrate an open annulus spine coupling 24 that joins the adjacent ends of the penetrator tube and the extension tube and for connecting the adjacent ends of additional extension tubes the couplings define a central opening or u201c annulus u201d that allows for passage of liquid and objects such as water filters the parts of the connector are shown separated in fig4 a coupled together in fig4 b and in cross sectional view taken along the length of the coupled section in fig4 c the female coupling body 24 of the coupling is fabricated with internally facing splines 34 and the adjacent ends of both tubes have complementary externally facing splines 35 that fit between the female splines 34 typically the female coupling body will be mounted on the upper ends of both the penetrator tube and extension tubes prior to reaching the well site when a tube is to be added to a previously installed tube the tube to be added will have its open end connected to the coupling that was previously mounted on the prior.