This mod allows you to get salt from water by leaving it to dry in a barrel, I decided that I would release this as unlike the other mods that provide similar functionality, this does not change any world generation. In fact you can add or remove this mod and there shouldn't be any lasting effects on your save from it.
One thing to note is that because of this, all water counts. So it is up to you to decide if you want to use any water, or just water with seaweed in it.
Download
SaltProduction.zip