There are many opinions in this respect. But all depends on the purpose of fasting. If the fasting is very much serious, if, for example, it is required to cure or ease a dangerous illness considerably and quickly, then certainly the most suitable water for such fasting would be distilled water. If the fasting’s task is just a little cleaning before a long juice-diet, the best water usually is well-filtered water. But in our case of a short-term fasting the proper training for the first attempts is to accustom the organism to this kind of therapeutic fasting. Therefore, the easier goes the first day the better.
And the simplest fasting is the water one, a fast with carbonated water. Initially the water should have neither minerals nor salts virtually. Read its label, there should be the content listed. If you are not sure, better to ask a seller or an assistant in the supermarket. Choose the most pure and most low mineral water of what you are able to obtain. Remember: there in that water should be nothing except carbonic gas and a very little addition (as minimum as possible) of minerals. It is your ideal water.
It does not need to be cooled, the room temperature suits the fasting best of all. Buy some bottles. You will need about one gallon in total, though better to buy it in smaller bottles because it will help you to have at least one bottle always with you. Please drink this water every time you feel thirst. And drink it even more if suddenly comes the appetite.
Even if you drink too much it is not dangerous. The main thing is: this day you should press down and quench both the thirst and the appetite. Fill in your body with water. Though there is no need of being addicted to water drinking too much. You can drink safely up to 12 pints of water that day. Or more. Or less. No restrictions.
WHY THE CARBONATED WATER IS BETTER
There is a rather little though important reason for that. The first advantage is that carbonated water has a weak acid reaction. Not to go into details, we can say that the weak carbonic acid in that water will never allow your organism to store up any salts neither in joints nor in blood vessels. It is very good for you. The second reason is the low salt concentration which was there in the water initially. During the carbonation process at the factory some salts drop down as a deposit and do not get into bottles.
As a rule, the carbonated water has a much lower percentage of salts than pure non-carbonated water. And again, it is very good. The third reason is taste. As a whole the carbonated water is a little bit tastier and gives a more fresh feeling than not carbonated waters. On fasting it is always a pleasure to feel a taste; it may calm the appetite down. And at last the fourth reason, the very important one, especially during the first days of fasting: drinking the carbonated water you will feel hundreds of microscopic bulbs of carbonic gas in your mouth; this usually simulates a food or something like food, thereby deceiving your digestion desires. In other words, with the carbonated water it will be easier to suppress the appetite, and refraining from meal will be slightly less problematic too.
PREJUDICES AGAINST CARBONATED WATER
Some people spread rumors and ridiculous prejudices against carbonated water. The especially baseless one is that the carbonic gas is harmful. To understand all the false ground and ignorance of such statement one should simply recollect an axiom.
Each person inhales 33 pounds of air a day in average, and sure, that person exhales exactly as much. In the exhaled air there is 4% of carbonic gas. Please let us count and see: within a day a person exhales some about 20 ounces of pure carbonic gas. It is absolutely normal, it is that same carbonic gas which is formed in each person as a result of ordinary breath.
But a two-pint big bottle of carbonated water contains just as much as 0.2oz of carbonic gas. It turns out that a common person exhales as much carbonic gas a day as we can collect from 120 big two-pint bottles! But even having thirst on fasting that person will hardly drink more than 4 of such bottles. That is 30 (thirty!) times less than that same person exhales in his normal state during that same day. Whether that little quantity is able to damage the organism? Definitely not. Moreover that gas is a good thing, a natural stuff that each of us produces every minute every day.