There is provided a plastic infiltration unit comprising: a top deck, at least one pillar extending from the top deck, wherein the at least one pillar includes a plurality of compartments, wherein at least one of the compartments is laterally enclosed, and wherein the top deck and the at least one pillar are produced in one piece. There is further provided a plastic base plate for use with a plastic infiltration unit. There is further provided a plastic infiltration unit side plate. There is yet further provided a plastic infiltration system for deployment underground comprising a plastic infiltration unit and a plastic base plate, wherein the at least one pillar of the plastic infiltration unit is received at the receiving location of the plastic base plate.