from everything i've read about fasting, (especially long fasts to completion), is that the body literally consumes all unnecessary or harmful tissue/bacteria/viruses. stones and/or tumours and whatever might be stagnating the lymph system are "eaten" by the body, therefore, they do not need to be first flushed out.
i don't visualize Water Fasting as having a hose in my mouth, with water flushing out every except my organs. i, and many others on this forum don't even drink very much water at all during fasting, because this can water-log your system, thereby actually slowing the healing and ketosis. i visualize my body as an entity containing thousands of years of wisdom... and with this vast intelligence, it seeks out and destroys the unnecessary/harmful parts while rejuvenating and repairing the parts we need to continue our survival.