Abstract: For the induction of underground collector mains, in particular for the ctruction of horizontal filter wells and drainage mains, at least one bore (1) having respectively an inlet aperture (3) and an outlet aperture (4) is introduced into predetermined layers of soil. Then a filter strand drawing in unit (5) which consists of an inner filter strand and an outer protective pipe is inducted into the respective bore (1) and finally the outer protective pump of the filter strand drawing in unit (5) is removed. The filter strand in unit is used as a tool consisting of an inner filter strand and an outer protective pipe. In a preferred further development, the intermediate space between the inner filter strand and the outer protective pipe is provided with filter sand and/or a filter gravel filling.