I found this Guide from the Environmenatal Working Group about safe drinking water. It is a good article, but I don't wholehearted agree with all of their suggestions.
Go here: http://www.ewg.org/files/EWG_safedrinkingwater.pdf
I believe the best water you can drink is Le Bleu Bottled Water. They use a patent pending purification process that enables them to produce the highest quality bottled water in the world. They can take water from any source and purify it through steam distillation. They eliminate the inorganic minerals and chemicals that could be in other waters.
Le Bleu is sodium free, and oxygenated with Ozone. Ozone is the most powerful sanitizer and disinfectant available. Ozone kills bacteria, toxins, mold, yeast spores, organic materials, parasites, and even viruses. And ozonation is only one step in Le Bleu's five step purification process. Le Bleu is also chlorine free, lead free, and Kosher certified.
I do believe that Le Bleu is the purest and best tasting water you can buy. I cook with Le Bleu and also make my coffee with Le Bleu. It makes the best cup of coffee I have ever had. You can get home delivery of their 5 gallon bottles. Do yourself a favor and just try Le Bleu. I do believe once you try Le Bleu's pure drinking water you will not want to drink anything else. I love Le Bleu!