Groundwater

Groundwater is water located beneath the ground surface in soil pore spaces and in the fractures of rock formations. A unit of rock or an unconsolidated deposit is called an aquifer when it can yield a usable quantity of water. Groundwater is recharged from the surface naturally; natural discharge often occurs at springs and seeps, and can form oases or wetlands.
Groundwater aren't confined only to the Earth: some landforms observed on Mars may have been influenced by groundwater.

Probable groundwater on Mars