There is a lot of survival training and information that has become a doctrine, and this knowledge is repeated over and over again. In fact, it is repeated so often
Water collection is a worthwhile endeavor for your off-the-grid life, as long as you do your research and take the right precautions before making any decision.
Drinking seawater will actually put salt into our bloodstream, not remove excess salt from it. When the salt level gets high enough, it will certainly kill us.
Bottled water is very expensive for what it is; plastic is filled with known carcinogens which may leach in the water; it’s a burden for the environment.