Space.com has more on the Wet Red Planet:
NASA’s Mars rover Curiosity has found that surface soil on the Red Planet contains about 2 percent water by weight. That means astronaut pioneers could extract roughly 2 pints (1 liter) of water out of every cubic foot (0.03 cubic meters) of Martian dirt they dig up, said study lead author Laurie Leshin, of Rensselaer Polytechnic Institute in Troy, N.Y.
“For me, that was a big ‘wow’ moment,” Leshin told SPACE.com. “I was really happy when we saw that there’s easily accessible water here in the dirt beneath your feet. And it’s probably true anywhere you go on Mars.”
It’s about as wet as most “dry land” on Earth.