I'm on a Water Fast right now and I have been drinking smartwater since the second week. The longest I had been able to go before in a Water Fast was 28 days. Now I am on day 30 and feeling none of the ill effects that I felt with the 28 day fast. The smartwater doesn't have sodium so I have been adding a pinch of salt to some of my bottles. I feel a lot more balanced with the smartwater so I would recommend it to anyone on an extended fast. The potassium levels in smartwater are very low, but it seems the combination of drinking a lot with a slower metabolism is sustaining the potassium levels in my body... so far at least. Since potassium is the electrolyte that tends to become depleted the quickest I was looking into supplements, but potassium supplements are rare and in minute quantities due to the possible side effects of potassium supplementation. They don't trust the general public with potassium, for good reason. Like too much Iodine can cause the symptoms of an Iodine deficiency... too much potassium can disrupt muscle function, even stopping the heart. Ok, rambling now. Have fun fasting guys!