Compare the relative ease of obtaining potable water from waste water, ground water and salt water.

In the subtopic Waste water treatment, this learning objective focuses on compare the relative ease of obtaining potable water from waste water, ground water and salt water. Within Using the Earth's resources and obtaining potable water, students should explain this idea in the exact curriculum context rather than as an isolated fact. Approved keywords for this objective include waste water. potable water means water that is safe to drink. Avoid students often confuse the ease of obtaining potable water from waste water with that from ground water and salt water, thinking they are equally easy to treat; instead to fix this, students should study the treatment processes for each water source, noting that waste water generally requires more extensive treatment compared to ground water, while salt water requires desalination, which is energy-intensive. For exam answers, compare the treatment processes for waste water, ground water, and salt water to understand their relative ease of obtaining potable water.