I have done a lot of fasting. The urine becomes very toxic when you are fasting. Normal urine is good for plants but I bet the urine from a fast can kill a plant. You do not want to put that waste back into your body that it has worked so hard ot get rid of. Pure water is fine. Especially all that excess salt it is getting rid of. Site below has info on fasting so can understand the process better. Also the page on natural healing tells about how fasting can help with depression.