They already found water on mars, it's just frozen.
Well, I meant liquid water. Ice on Mars is old news.
That's unfortunately impossible for the vast majority of Mars' surface. The average surface air pressure on Mars is lower than water's triple point, therefore water can't exist in the liquid phase regardless of what the temperature is. (If you warm ice at such pressure, it just sublimates instead of melting. See
phase diagram). That said, the pressure is variable with seasons, and at very low altitudes like Hellas Basin can be high enough to support liquid water, if the temperature is also above 0°C.