We present Monte Carlo radiative transfer models for B335, S140, and ρ Ophiuchi A that simulate the emission line arising from the 557 GHz 110 → 101 ground-state transition of ortho-H216O. These models reproduce the line profiles with a combination of turbulent and macroscopic motions, and are consistent with gravitational infall in ρ Oph A. We cannot, however, discriminate infall from outflow for S140. Our models are consistent with ortho-H2O abundances relative to H2 of 2 × 10-8 and 4.5 × 10-9 in S140 and ρ Oph A, respectively, and an upper limit of 4 × 10-6 (3 σ) in B335, assuming the ratio ortho-H2/para-H2 = 0.1. We quantify the impact of dust continuum emission on the derived abundances.