Not the OP, but when I fasted I only drank water, usually distilled. You don't eat anything, hence the term water fasting. I should mention that I personally got weekly blood tests to keep track of the vitals (especially potassium levels) and this is something you definitely should do especially if it's your first prolonged fast.

Interesting. Why did you stick to distilled water, as opposed to having some (non-caloric) electrolytes?

Most people do not reach a point where their electrolyte levels are dangerously low when undertaking a prolonged fast of up to 40-45 days. Low levels of electrolytes are an indication that your body is unable to continue in a fasting state for one of several reasons, and it must be stopped.

IMO, artificially supplementing those during the fast will throw off your body's sensors if you will of knowing when something is abnormal.

Only water. Tap water or bottled water, not distilled for me. Other than that I ate nothing, no vitamins or electrolytes or anything, just water.

I find this remarkable. Not saying that I absolutely don't believe you, but I'm struggling. This would seem more like starvation than fasting, and sounds potentially very dangerous. For a little context: http://www.scientificamerican.com/article/how-long-can-a-per...