Amount - depends on activity levels, but try to make sure the color of your urine never gets dark, cuz that's a sign your kidneys are working hard to get rid of toxins in very concentrated urine.

Also. Fluids is not water. PERIOD. If you get nothing else but get this then it will mean the biggest difference to the quality of your life from now on.

I've tried doing that some time ago for a few days but what happened was I never felt thirstier. It was just half a teaspoon into 5.5 liters of water, in the end I gave it up. Maybe the right way is half a teaspoon of seasalt after every ten glasses of water, as prescribed in the book.