H₂O diagnostic diagram from Banzatti et al. (2024), adapted to include the measured line ratios for CX Tau. Data points from Banzatti et al. (2024) (excluding data points with upper/lower limits) are indicated with black circles and the data point for CX Tau is indicated with a blue star. Three models from Banzatti et al. (2024) are shown: the model with a hot (850 K) and warm (400 K; optically thick) component is shown as a gray solid line (labeled “H + W (TK)”), the model with a hot (850 K) and warm (400 K; optically thin) component is shown as a dashed, gray line (labeled “H + W”), and the model with a hot (850 K), warm (400 K), and cold (190 K) component is shown as a dashed, light gray line (labeled “H + W + C”).