A drainage system for connecting a rack drain on a mobile plant rack to a stationary building drain, wherein the plant rack is operable to slide between first and second positions wherein the building drain is proximate and distal thereto, respectively. The drainage system comprises at least one horizontal support proximate to the bottom of the mobile plant rack and a flexible conduit fluidically connected to the discharge end of the rack drain, extending arcuately between a receiving end fixed within the interior rack space and a discharge end fixed outside of the interior rack space, wherein the discharge end is fluidically connected to the stationary building drain. The receiving end of the flexible conduit is raised above the discharge end and the flexible conduit is supported by the at least one horizontal support to maintain a generally down slope grade.
