On tap

I recently read about a site called Tappening.com which urges people to drink tap water and forgo bottled water.  The substance of the site isn't amazing, but the idea is definitely something I find timely.  It certainly fits into the current conversation about buying locally and reducing one's carbon footprint.  So I definitely support the concept and the attention this movement (I don't know that it can be called a "movement" yet) has focused on something as simple as this.  

I've started to wonder, however, whether people can really change their habits, rather than making small adjustments to their routine.  I wonder if this will be a fad like the Atkins diet was a few years back.  That was a cause that was taken up by the media and business, just like current green campaigns.  People made serious commitments and changed their ways in the name of cutting carbs.  But now, a few years later, that's mostly gone.  

So can people make changes -- to their commutes, to their buying habits, to their water-drinking practices -- that become a permanent part of their lives?