So filtered water is just fine as long as you are not adding anything else in it. Water only means, water only as per thirst.
Dry fast is ok, but I suggest do dry fast for two days in the beginning because you need water more at the end of your fast to move the toxins and more strength.
Take one day at a time, rest, stay warm and drink warm water and you will be fine.
After you complete your fast eat only raw fruits and vegetables, a few weeks later add Kefir, Kombucha, Kimchi and Sauerkraut to your diet. Donít drink alcohol, sugary foods and processed junk. This will help you with IBS.