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The crystal structure of the title compound, C29H33ClN2O3.2.25H2O, has been determined. The three C-N(piperidyl) bond lengths reflect the tetracovalency of the piperidine N atom. A strong intermolecular hydrogen bond between the hydroxyl and the N-oxide of neighbouring molecules forms endless chains in the b direction of the C2/c space group. The positions of the water molecules are partially occupied.