The Water we drink is the most important thing we put into our bodies. Distilled Water is the best because of TDS (total dissolved solids). It has zero (or thereabouts ). Reverse Osmosis water comes close.
Filtered Tap Water is okay for removing Chlorine, but does not remove the solids. These solids are inorganic, and cannot be used by our bodies. Therefore, what can't be eliminated is stored....making for health problems later in life.
My tap water has about 250 ppm (parts per million) of TDS. I was so concerned about my water that I bought a Distiller......WY
P.S. What you do short-term doesn't matter. For long-term...think Distilled...not just while Fasting, but for everything.