Can a human survive on brackish water?

The Baltic Sea’s water at the surface, in the middle, has salinity of 6% to 8%, compared to the oceanic average of about 35%. If you were adrift in the Baltic Sea, could you survive by drinking the water? ISTR reading in a book or seeing in a documentary of an RAF study that showed downed fliers could extend their water supply by mixing in up to 50% sea water. (Sorry, no cite.)

Here’s a chart of guidelines for salinity:

Good drinking water for humans (provided there is no organic pollution and not too much suspended clay material)

Can be consumed by humans although most would prefer water in the lower half of this range if possible

Not recommended for human consumption, although water up to 3000mS/cm could be drunk if nothing else was available

Can you provide a cite for where you got 35% salinity? That can’t possibly be 35% salt. Unless I misunderstand the definition of salinity.

Sorry, I was dead-tired last night and I mis-read. Searching now, it looks like it’s 35 parts per thousand, or 3.5%

Here’s what I read on Wiki: