Is water on Mars even exciting? We're already quite certain there is a ton of water on Mars... in the form of ice. The exciting discoveries are evidence of liquid water.
> The bulk of the northern ice cap consists of water ice; it also has a thin seasonal veneer of dry ice, solid carbon dioxide. Each winter the ice cap grows by adding 1.5 to 2 m of dry ice.
> The part of the cap that survives the summer is called the north residual cap and is made of water ice. This water ice is believed to be as much as three kilometers thick.
> The bulk of the northern ice cap consists of water ice; it also has a thin seasonal veneer of dry ice, solid carbon dioxide. Each winter the ice cap grows by adding 1.5 to 2 m of dry ice.
> The part of the cap that survives the summer is called the north residual cap and is made of water ice. This water ice is believed to be as much as three kilometers thick.
https://en.wikipedia.org/wiki/Martian_polar_ice_caps
That's a lot of water!