The "pink" amount appears to be in the range of 1-3mg/L. So the LD50 for an 80kg man would be ~30,000 liters orally. That would certainly be lethal. The rule of thumb for this stuff is also "If it's pink, it's safe to drink"[1], as in pink is the minimum concentration to ensure safety. The only reason to avoid higher concentrations is that it will stain heavily.
1: http://bluecollarprepping.blogspot.com/2014/08/potassium-per...