Embodiments described herein are related to water management units for extracting water from moist soil. The units extract water and collect it to be siphoned away as waste water or for later use. A water management unit comprising: an elongate collection portion; and an extraction portion arranged to discharge extracted water into the collection portion, wherein the extraction portion comprises at least one rib extending laterally from the collection portion along a length of the collection portion. Water is collected by capillary action.