Actually, there is one thing you need to do to tap water to make it better for you…
Let it sit for a while before drinking, preferably not in an air tight container.
This will allow the Chlorine to disipate from the water (not all, but a lot of it). Chlorine has several negative effects on the human body (it is after all a poisonous gas that is fatal to humans); one of those is how it bonds to Calcium as Calcium Chloride. Chlorine can actually serve to REMOVE Calcium form the body since calsium bonds better with chlorine than with many other minerals (that is why sodium chloride is used to “soften” water, the calcium bonds to the chloride more easilly than the sodium does).
If you really want a good natural source of calcium, every time you eat eggs, leave a tiny amount of shell (crushed) in the eggs, and when you eat meat, gnaw the meat off the bones (giving you a small amount of calcium scraped off by your teeth).
BTW: one of the reasons Fluoride has to be added to water is to counter the negative impact of Chlorine on dental enamel… Chlorine, on its own, will soften and discolor teeth.
So… tap water is fine. Just keep a pitcher of it in the fridge and let it sit for a while before drinking it.
Final comment: that reverse osmosis water crap (like Dasani) tastes METALIC to me, like chewing on a piece of alluminum foil. I’d rather drink the sulfur and iron laden water from the well where I grew up in Pennsylvania than to drink that crap. Sulfur tastes better than alluminum IMHO.