[familyop]

"By desalinating water on any large scale, one necessarily increases the salinity of the remaining water left behind."

Assuming that the salt from the filtered water would be dumped back into the ocean? ;-)

[MrB]

Yep, the question has to be asked - where did the “salt” (and other minerals) come from in the first place? The land. Rain. Rivers. Erosion. Ocean.

Now, an aside. Give the current rate of depositing of salts in the ocean, how “salty” should the ocean be if it were billions of years old?