  Extragalactic water vapor masers with 50, 1000, 1, and 230 solar (isotropic)
luminosities were detected toward Mrk1066 (UGC2456), Mrk34, NGC3556 and Arp299,
respectively. The interacting system Arp299 appears to show two maser hotspots
separated by 20 arcsec. A statistical analysis of 53 extragalactic H2O sources
indicates (1) that the correlation between IRAS Point Source and H2O
luminosities, established for individual star forming regions in the galactic
disk, also holds for AGN dominated megamaser galaxies, (2) that maser
luminosities are not correlated with 60/100 micron color temperatures and (3)
that only a small fraction of the luminous megamasers detectable with 100-m
sized telescopes have so far been identified. The slope of the H2O luminosity
function, -1.5, indicates that the number of detectable masers is almost
independent of their luminosity. If the LF is not steepening at very high maser
luminosities, H2O megamasers at significant redshifts should be detectable with
present day state-of-the-art facilities.
