Because the news presents "a hydrate" as "water." It's not, of course.
Ojha notes that they haven’t actually observed water flowing on Mars. The team took their data from the CRISM instrument on the Mars Reconnaisance Orbiter, which, frustratingly, only observes the surface every day at 3 pm. That’s when Mars is at its hottest and driest, so any liquid water oozing on the surface would have long since evaporated by the time MRO laid eyes on it.
Still, the water left a distinctive chemical trace. “Whatever is flowing on Mars is hydrating the salt,” Ojha says, “and we’re seeing that hydration in the spectral signature.” After extracting spectral information from pixels of the CRISM instrument’s data, Ojha and his team determined that the salts—magnesium perchlorate, magnesium chlorate, and sodium perchlorate—had water molecules interspersed in their crystal structures. That’s pretty strong evidence that they were deposited by flowing water.
we know that there is ice on mars - another form of water no biggie.
but liquid water is big, because it is - atleast for us - the base of life, so there might be aliens right now living on mars :9
Concrete - hydrated.....
Geophysically, there is nothing that would prevent large underground liquid water deposits on Mars.