Ick...not even a chaser?! Bentonite has an amazing surface area and can absorb an incredible amount of water. Mixing it with water helps to increase the surface area. Here's a great link for lots of info on bentonite:
One tablespoon is plenty...just mix it in a glass of water. The amount of water is not so important unless you add psyllium to it. Then you should mix it with 8-10oz of water or diluted juice and follow it with another 8-10oz glass of water.