Final answer:
We cannot use ocean water, glacier melt, ice caps, and polluted water sources for our daily purposes due to high salinity or contamination. Only approximately 1% of Earth's water is available as drinking water, underscoring the necessity of water conservation and preservation.
Step-by-step explanation:
There are sources of water that we cannot use for our daily purposes, primarily because of their salinity or pollution levels. This includes the vast majority of water found in the oceans. Ocean water contains high levels of salt, which makes it unsuitable for drinking or many industrial and agricultural uses without undergoing a costly and energy-intensive process known as desalination. Glaciers, ice caps, and polluted bodies of water also contribute to sources that are not readily available for use. Despite the Earth being covered by water, only about 1% of this is accessible and clean enough to be considered drinking water. Therefore, preserving and protecting our limited freshwater resources is of utmost importance.