Fresh waters occur in rivers and lakes as surface water and in underground reservoirs as groundwater.

The amount of surface water in rivers and lakes is less than 1% of the amount of water in groundwater, glaciers and icecaps.

However, the surface water recycles readily, on the average every 12 days.

The groundwater does not recycle readily, sometimes taking more than 1000 years.

Societies than rely solely on groundwater are bound to deplete the resource.

Who owns the groundwater?  [Video]

California relies on both surface and groundwater, about 50% each.