What are water sources that would not be easily used to supply human water needs?

Water sources that are not easily usable for human needs include saline water from oceans, which requires extensive desalination processes, and polluted water bodies contaminated with chemicals or pathogens. Additionally, glacial ice, while a significant freshwater source, is often inaccessible for direct human use without proper infrastructure. Lastly, water trapped in deep aquifers may be difficult to extract due to technological and economic constraints.