Integrated intensities of selected rotational transitions of ortho-H₂O plotted against the excitation energy of the emitting level, expressed relative to the energy of the J = 0 = K ground state of para-H₂O. Results are shown for shocks with n_H   =   10⁵ cm^-3, V_s = 30 km s^-1 and b = 1.5 (red), b = 2.0 (green) and b = 2.5 (blue). Full circles: model M1; open circles: model M2.