Infrared spectra from 25 to 4000 cm(-1) have been recorded of water (H2O, D2O and (H2O)-O-18) matrix isolated in neon, argon, and krypton matrices. Intermolecular absorption bands of different isotopologues of the water trimer and tetramer have been assigned from concentration dependencies and diffusion behavior, using the well-known mid-infrared trimer and tetramer absorption bands as measures of the trimer and tetramer concentrations. The results are compared to ab initio calculations.