Melting-freezing dynamics of water confined in three MCM-41 materials with pore diameters of 2.0 nm, 2.5 nm and 3.7 nm was analyzed using dielectric spectroscopy method. Obtained results show, that reorientation of water molecules is strongly affected by confinement and interaction with the pore surface, which leads to the formation of highly disordered hydrogen bonded network. Defects of this network play the key role in the overall relaxation of confined water.