Most of the water flow in the root takes place via the apoplast, because

Water flow in the roots occurs via the apoplast because the cortical cells are loosely packed and hence offer no resistance to water movement. The inner boundary of the cortex, the endodermis is impervious to water because of a band of suberised matrix called the casparian strip. Water molecules are unable to penetrate the layer, so they are directed to wall regions that are not suberised, into the cells proper through the membranes.