Line luminosity of the water transitions normalised to the luminosity of the H₂O 2₀₂–1₁₁ (988 GHz) line as a function of the upper energy level (E_u) of each transition considering only the contribution from the cavity shock component. The solid blue, black, green and red lines corresponds to the averaged value of the normalised intensity for the low-mass Class 0, Class I, intermediate-mass and high-mass YSOs respectively. The grey dashed line represents the average values of the sample presented in Yang et al. (2013), the pink and light blue dashed lines indicate the values of the strong AGN- and Hii+mild-AGN-dominated galaxies, respectively. The 2₁₁–2₀₂ (752 GHz) line has an E_u/k_B = 137 K and the 3₁₂–3₀₃ (1097 GHz) an E_u/k_B = 249 K.