I haven't done it yet, but you should be prepared in drinking the additional water. It does make a difference. If you don't think you can then you might want to research a little more on a cleanse that is more appropriate for you. I just finished 1 month on the Colonix and haven't had the "major" cleanse, but it is pretty easy, it's just more than the P&B. I just ordered the stuff for the P&B and from what I've read the clay can cause major backup if you don't have sufficient water to push it through.