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:

0-800mS/cm
Good drinking water for humans (provided there is no organic pollution and not too much suspended clay material)

800-2,500
Can be consumed by humans although most would prefer water in the lower half of this range if possible

2,500-10,000
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: