We know that water is not at all uncommon throughout the universe. We also know, since the launching of the Kepler telescope, that there are millions of millions of millions of planets, only in our galaxy.
Now this. There is evidence of FLOWING water on Mars!!! A planet that we thought barren, only a few years ago.
Life as we define it -as to say, carbon-based, quite a narrow definition of life in my opinion- might not be as rare at the end of the day...
We truly live in a time of amazing discoveries...
This below is the link (copy and paste) to more information information on flowing water on Mars.
A Mind full of Ideas