The formulation of water vapor continuum absorption under non-LTE vibrational conditions is presented. The semi-empirical approach of Clough, Kneizys and Davies is extended to non-LTE vibrational conditions assuming rotational-translational LTE. Self- and air-broadened H216O continuum is simulated in 0-5500 cm-1 spectral region at the constant temperature T = 288 K. The possibility of marked nonequilibrium bleaching of continuum in certain spectral regions is demonstrated and explained by full and partial population inversion effects between H2O energy levels. The absorption increase in some other regions is also obtained. A more flexible method of continuum characterization is proposed based on the use of several semi-empirical chi-functions for H2O line shapes, which should be determined separately for each band using experimental data. Possible experiments revealing the nature of water vapor absorption continuum (monomer/dimer) are discussed based on the theoretical results obtained.