Ratio of the H₂O line luminosity over the IR luminosity (L_H2O/L_IR), as a function of L_IR, for the two Hot DOGs. Top: W0149+2350 in comparison to literature sources with detected H₂O(2₀₂−1₁₁) emission, labelled based on their classification (van der Werf et al. 2011; Combes et al. 2012; Bothwell et al. 2013; Omont et al. 2013; Riechers et al. 2013; Falstad et al. 2015, 2017; Yang et al. 2016; Liu et al. 2017; Oteo et al. 2017; Apostolovski et al. 2019; Jarugula et al. 2019). Also shown are the average ratios found by Yang et al. (2013) for nearby IR galaxies. Bottom: W0410−0913 in comparison to literature sources with detected H₂O(3₁₂−3₀₃) emission, labelled based on their classification (Riechers et al. 2013; Falstad et al. 2015, 2017; Liu et al. 2017; Oteo et al. 2017); the average ratios found by Yang et al. (2013) for nearby IR galaxies are also shown.