http://www.nytimes.com/yr/mo/day/national/index-science.html
 
At times people here discuss water quality and the measures they take.
Scroll down this page to the "Personal Health" column to learn a very large
amount about water quality and standards, how rare problems with tap water
are, what standards are actually more strict than those for tap water and
which are not, what filters do what, etc.
 
[Moderator's note: Registration required.  That page changes quickly, but
the article is still there as of 19 Jun, 1:30am Eastern Time.  BIG]
[Posted in FML issue 3117]