Velocities of the water maser groups in the CO latitude-velocity plot (white dots). The CO emission was integrated over a longitude range from 12.625° to 13.0°. The units of the color bar are degrees Kelvin. The water masers in W33 and in G012.88+0.48 are associated with clouds at 34.6 km s^-1 and 30.9 km s^-1, respectively. The water masers at −1 km s^-1 (W33 Main) and 58 km s^-1 (W33 B) seem to be outliers.