NOEMA 1.37 mm (219 GHz) continuum image toward W3(H₂O) in grey with levels starting at 6σ and increasing in steps of 6σ. The black contours correspond to the cm emission from Wilner et al. (1999). The positions of H₂O masers obtained from Hachisuka et al. (2006) are plotted as yellow triangles. The blue and red arrows show the directions of bipolar molecular outflows from Zapata et al. (2011; see Fig. 6). The synthesised beam size of the cm emission (0.′′ 21×0.′′19, PA = 68°) is shown in black in the bottom left corner. The synthesised beam size of our mm continuum image is shown in grey in the bottom left corner.