Observations of 10 transitions of HCO+, CO and CS isotopomers were taken with the IRAM 30 m telescope for a sample of 28 methanol maser sources detected in the Torun unbiased survey of the galactic plane. About 64% of the sources show line wings in one or more transitions, indicating the presence of molecular outflows. Two sources show evidence for infall motion. Comparison of the widths of line wings and methanol maser emission suggests that the 6.7 GHz maser line traces the environment of massive young stellar objects of various kinematic regimes. Calculations based on the CO and HCO+ lines and the CS line intensity ratios refine the physical parameters. Specifically, a gas density of <107 cm−3 is sufficient for strong maser emission and a high methanol fractional abundance (>5×10−7) is required.