Western Lake Erie Waterkeeper Association
"Many chemical contaminants present in drinking water sources, such as pesticides or naturally-occurring toxins, are not removed by standard drinking water treatment processes."
-- Centers For Disease Control and Prevention, source
Furthermore, additional contaminants enter our drinking water as byproducts of treatment chemicals and on account of the pipes our water passes through.
Want to know what's in your drinking water? Click here.
Arsenic has been used as a poison since at least the 8th Century, and it is labeled a carcinogen in the European Union.
Depending on where you live, you might find, in addition to all the other bad stuff, that you have arsenic in your water. One of the projects of the Centers For Disease Control and Prevention is an "investigation of the extent of human exposure to arsenic in tap water."
The US EPA has information on arsenic in drinking water here. Information from the NRDC is available here. Additionally, arsenic is used in chicken feed. To read more about this, click here.
Western Lake Erie: The Warmest, Shallowest, "Fishiest" Area of the Great Lakes
To learn more about the Waterkeeper Alliance, click here.