Artist's rendering of moon impact mission
How much water is on the moon?
Scientists think there is quite a bit, potentially, hidden in dark craters.
In addition, moon rock samples also have been found to contain water. Even rocks on earth, from magma to sedimentary deposits like borax, also contain water molecules in crystalline form. It's possible that the moon had a much wetter past, and that life in some form may exist, if indeed the presence of water is significant - even in an underground, microscopic state. Remember the moon is only 250,000 miles from the earth, or approximately ten earth diameters away.
Water-bearing moon rocks
Asteroid or comet impacts on the earth over the last 1.3 billion years could have blanketed the moon with life-bearing debris which could have retained life, if it was kept warm enough and distant enough from the vacuum of space.