Radex predictions for the ratio between the p-H₂O (1₁₁ − 0₀₀) (at 1113 GHz) and the o-H₂O (3₁₂ − 3₀₃) (at 1097 GHz) lines as a function of the H₂ density for four values of kinetic temperature (100, 300, 500, and 1000 K) and two values of o-H₂O column density (10¹³ and 10¹⁶ cm^-2). The shaded bands represent the water ratios observed for the compact and extended components at R2, i.e., the R2 position and a position (10′′, −10′′) offset from R2. The HIFI water line intensities are integrated in the line wings, between 10 and 60 km s^-1, at the original angular resolution of the spectra (19′′).