The fact that there is some brine on the surface is a promising indication that there could be larger amounts of water below the surface, perhaps in the cave systems and collapsed lava tubes like those found at Pavonis Mons.
It seems not actual water but only "evidence of transient water" (Thanks for the link Ray).
The article seems to state the analysis of soil samples shows that there is evidence of water formation in the top 5cm of the subsurface of soil which then evaporates in the morning sunrise. So not liquid water found just evidence of water formation, not even enough to be directly detected.
