Final answer:
The finite availability of freshwater, which comprises only 4 percent of Earth's water with much of it in glaciers, coupled with high usage in agriculture and other activities, contributes to the scarcity of accessible drinking water.
Step-by-step explanation:
The question is focused on the availability of fresh water on Earth and its sufficiency for continued usage. While 70 percent of the Earth is covered with water, only a small fraction of that is freshwater, which is essential for human consumption and various activities. The fact that only 4 percent of water on Earth is freshwater, and a significant portion of it is locked up in glaciers, leads to a scarcity of accessible drinking water in many communities. Moreover, human activities such as agriculture and industry require vast amounts of water, leading to a further strain on the resource. For example, it is estimated that one pound of beef requires 1,800 gallons of water, while a typical person in the U.S. uses about 100 gallons per day.