Who says life needs water, maybe life on Earth but you can't just say you need water. It's like saying you need wings to fly. Also how would we know what Aliens look like for all we know Planets could be life they have a system of workning and growing maybe they don't breath or have a heart but neather does bactiera. We could be surronded by alien life but so simple minded not to notice it or just so use to it we don't ask why. And who is to say what is life?

Actually, it's always bugged me when I hear this equation limited to similar environments to our own human-centric climate. There are creatures alive in the depths of the ocean that live in conditions that are anything but pleasant. So who's to say that on some hellish, briny, acidic, volcanic, all-water planet there aren't intelligent creatures evolved from mean little shrimp-like buggers feeding on algae and protein growing near volcanic vents at pressures beyond imagination around a binary star system? That would increase the number of chances of finding life rather dramatically I would think.