Humans need to withdraw groundwater in order to use it. Groundwater comes from aquifers that formed underground over long periods of time , sometimes several thousand years . By drilling wells into the ground , humans can pump water out of these aquifers . The rate at which humans withdraw groundwater is much faster than the rate at which these aquifers recharge , or refill As a result , the groundwater supply is being depleted , or reduced . The total volume of groundwater that has been removed and not replaced is called groundwater depletion. As groundwater depletion increases, groundwater will become more difficult to find and more expensive to withdraw. Which statement correctly describes how groundwater is affected by human activity?