Luminosity correlations between the H₂O 2₁₂–1₀₁ line at 179.527 μm and (from top to bottom) CO 14–13, CO 24–23, [O i] at 63.18 μm, and OH at 84.6 μm, for 16 out of 18 objects (all luminosities in units of L_⊙). Full array and central spaxel luminosities are shown in the left and right columns, respectively. Red circles correspond to Class 0 sources and blue circles to Class I sources. Empty symbols show the compact sources, whereas filled symbols denote the extended sources. The Pearson coefficient of the correlation (r) is shown.