To complete a groundwater monitoring site including several monitoring points disposed at different depths, the piping includes a single multi-conduit pipe (1) having a smooth, tightly packable outer wall and being composed of individual pipe lengths (4) which are coupled to each other in a sealed relationship. The pipe lengths (4) are subdivided in the longitudinal direction into several conduits (6a-6d) by partition walls (5) and are coupled to each other in such a fashion that their conduits (6a-6d) are in relative alignment at the junctures and not reduced in area. For the purpose of providing filter sections for the admission of water, individual pipe lengths are provided in their outer wall with filter slots (9) in the area of one or several conduits.