some people do well on a water fast, others like me just can't do a Water Fast at all. i think juice is far superior to the Master-Cleanse and water because you get all kinds of vitamins minerals and enzymes in a very esaily assimable form. you BOTH give the digestive system a rest AND get lots of nutrients. also fresh juice has a strong life force, which water doesn't and the Master-Cleanse has only the life force of the lemon.
but i always supplement at least one juice a day with a liquid minerals supplement like this one