Seepage of groundwater from adjacent locations with higher groundwater is one of the bottle-necks for soilgrown greenhouse crops. This obstructs the application of reuse of drainage water at greenhouse holdings. In an attempt to reduce the quantity of seepage an experiment was carried out at a commercial greenhouse with lily. The groundwater table in the greenhouse was increased by raising the outlet of the drainage in the collection tank. The quantity of seepage water could be reduced by about 40% . The moisture in the root zone was hardly affected. The success of this method depends greatly on local conditions, a general recommendation can therefore not be given.