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It depends on the bottled water and the tap water in question. Certainly the tap water where I live now is outstanding. I drink bottled water for convenience. On the other hand, some years ago I lived in Fairfax County Virginia. I think they got their water from the Potomac. Every summer, as the water level would go down and hence the bacterial count would go up, they had to crank up the chlorine to purify the water. It had so much chlorine in it that when we ran the shower the apartment smelled like a swimming pool. Even our cats wouldnt drink the water. We used bottled water for any internal consumption in the summer; coffee, drinking, and water for the cats.