OH vs. H₂O  maser luminosity including all sources where masers from both species have been searched for. Green arrows represent the galaxies hosting only H₂O  maser emission, red arrows are those sources hosting only OH maser emission, and filled triangles are galaxies where both H₂O  and OH masers have been detected. Upper limits for the undetected maser species are set to the detection luminosity threshold (3σ) of the survey in that maser transition. The dashed lines indicate the separation between kilomaser and megamaser regimes as found in the literature (for H₂O  masers, see Sect. 1; for OH masers, see Henkel & Wilson 1990). The question mark associated with the position in the plot of UGC 5101 is explained in Sect. 4.3.