Relationship between the infrared luminosity, L_IR, and the ratio of the L_{H2O (220 − 211)} and L_IR of BR 1202-0725 (red hexagons) and for a sample of local galaxies (blue hollow squares Yang et al. 2013). We show a least-squares fit to all galaxies (blue line, slope of 0.19 ± 0.02). To make the estimates for the QSO and SMG, we used the infrared luminosities from Salomé et al. (2012). Other estimates from the literature are a few times higher (Wagg et al. 2014; Lu et al. 2018) and would yield values that have greater consistency with the best fit shown in the figure.