H₂O 2₀₂–1₁₁ / 2₁₁–2₀₂ versus H₂O 3₁₂–3₀₃/ 3₁₂–2₂₁ line ratios for various H₂O column densities and H₂ densities from RADEX models. The four panels are for different line widths corresponding to the width of each of the offset components. The temperature is fixed at 750 K. The different line styles correspond to different H₂O column densities and the dots are for different H₂ densities. The observed ratios are scaled to the same beam and marked with 15% error bars in both ratios.