Rotational diagram summarizing the disk-integrated H₂O line detections in the HL Tau disk with ALMA in the (sub)millimeter (cyan), Herschel PACS in the far-IR (pink), and Gemini North in the mid-IR (orange). Left: rotational diagram without a correction for the difference in the continuum optical depth for the various lines. Right: rotational diagram with a correction factor derived from a thermochemical model. The shaded points in the right panel are identical to the non-shaded points in the left panel.