[quote=Damosis]
Interested, but boiling sea water removes the salt and bacteria, meaning the purification gear is unneeded.
[/quote]

Good point, but rather than set up an industrial-scale water boiling operation, why not pump it out through a specially designed filter? And what about poison? Them tribals start chucking dead animals into the water, it might take more than boiling to kill some of the more heat-resistant strains of bacteria. 

See it like the carpentry tools. Yes, you could saw a tree down with a sharpened rock, with enough effort - but why bother when you could grab your trusty saw?