For drinking water - I could control clouds to rain and catch it on deck, but that involves having rainclouds at sea when you might want to avoid that.
Referencing the topic https://forum.atlas-games.com/t/salt-mine-spell/9715/1 (which is about turning seawater into salt for sale), let's turn it around and have a spell that turns water into vapour, leaving the salt behind, and you catch the vapour.
ReAq 3 turns water into steam. Adding a terram requisite as ReTe can be used to move the salt or hold it in place. ReAq(Te) Base 3, +1 touch range, +1 duration concentration, +1 terram requisite - total 10. This will turn a pot of salt water into water vapour and leave the solid salt behind, if you catch the vapour in a separate pot, when you end concentration it condenses back into water.