Top: comparison of HIFI spectra for H₂O transitions connecting with the ground state: o-H₂O (1₁₀ − 1₀₁) shown by the dashed black line and p-H₂O (1₁₁ − 0₀₀) shown by the thin solid red line. The spectrum shown in blue (solid thick line) is the residual emission after subtracting the emission of p-H₂O (1₁₁ − 0₀₀) line from the o-H₂O (1₁₀ − 1₀₁), referred to as the extended component. Bottom: comparison of the extended component seen in the H₂O (1₁₀ − 1₀₁) line (solid black line) with the o-NH₃ (1₀ − 0₀) (dashed red line) and the CH₃OH (6₁₆ − 5₀₅) (dotted blue line) spectra obtained from Codella et al. (2010) (left panel). Comparison of the o-H₂O (1₁₀ − 1₀₁) line at 556.9 GHz observed in B1 (extended component; solid black line) and in L1157-B2 (dashed red line) from Vasta et al. (2012). In all panels the vertical dashed line marks the ambient LSR velocity v_LSR ~ 2.6 kms^-1 (Bachiller & Pérez Gutiérrez 1997).