The EHSO website answers many questions on this subject.
Although I have seen many programs like the one recently shown on Frontline, I found this most telling on the EHSO site where they say……

“While bottled water marketing conveys images of purity, inadequate regulations offer no assurance. The National Resources Defense Council, a well-organized environmental interests group, funded a study to compare bottled drinking water against ordinary tap water. Unless you remember the problems that Perrier had over 10 years ago with contamination in their water, the results may surprise you. Those of us who work in environmental sciences and engineering usually drink tap water, if that tells you anything! EHSO is studying the NRDC report, and we will shortly provide our summary and opinion. In the meantime, these pages link to the report so you can read it, too.

And if the absurdly high price of bottled water and this report doesn’t convince you to switch to tap water (with a good water filter on it!) then also consider the following:

Leave an unopened bottle of water from the store in a sunny location for a month. Still want to drink it?

Dentists report a dramatic rise in cavities for the first time reversing the trend of decline. One possible reason: bottle water contains no Flouride, which protects teeth; while tap water is usually fluoridated.

So I guess nothing has changed for 20/20 did a segment a few years back saying the same thing..that tap water is essentially safer than the bottled.

Additionally, a check of the NRDC report can answer many questions for those seeking more info or answers. Appendix A and B alone would keep me from ever buying the nasty stuff.

NRDC’s Report——-Executive Summary
Chapter 1: Principal Findings and Recommendations
Chapter 2: Exploding Sales – Marketing a Perception of Purity
Chapter 3: Bottled Water Contamination – An Overview of NRDC’s and Others’ Surveys
Chapter 4: Gaping Holes in Government Bottled Water Regulation
Chapter 5: Misleading Bottled Water Labeling and Marketing
Chapter 6: Ensuring Consumers’ Right to Know About Bottled Water
Appendix A: Bottled Water Contaminants Found
Appendix B: Documented Waterborne Disease From Bottled Water
Appendix C: Summary of State Bottled Water Programs
Report Credits and Acknowledgements