I've read a few different things - one says you can take the shakes for up to 6 months, but I can't remember where I read this! From what I remember it seemed to be a reliable source though. Something else I read said to continue taking the shakes as long as mucoid plaque is being eliminated. I read this in the booklet I received with some powdered Bentonite I got from http://www.manifesthealth.co.uk
Also, regarding only Bentonite in water - on my bottle of liquid Bentonite, it says 'may be taken for a duration as long as desired'.