Do drink tap water? Do you know where your local water comes from? Around here our water contains flouride and chloromide. It also has trace amounts of lead and other minerals not in high enough concentration to cause me concern. The city monitors the quality constantly. I have replaced most of the old plumbing in my home with copper but there are a few places where I didn't have acess. So that is a minor concern. I also realize that no system is flawless so it is possible that contamanints may get into our water system. For that reason I use a carbon block filter for my drinking water at home. This filter system is not perfect either but it is one more level of protection. Plus the water tastes better. I will drink tap water when I am out . I don't like drinking bottled water so sometimes I carry a stainless steel bottle filled with water from my home. Most of our water comes from soil runnoff from the snowpack in the Sierra Mountains. It is collected in the Hetch Hetchy reseviour north of Yosemite. I think it is a good idea to know the source of my water.