The following are extracts from various sources highlighting the various health risks you could endure from drinking normal tap water:

www.waterwarning.com
"According to the U.S. Council Of Environmental Quality, ' Cancer risk among people drinking chlorinated water is 93% higher than among those whose water does not contain chlorine."

www.waterwarning.com
"Breast cancer.. has recently been linked to the accumulation of chlorine compounds in the breast tissue."

www.waterwarning.com
"Most lead in drinking water comes from lead lined pipes, lead solder and brass plumbing fixtures inside your home."

Consumer Reports
The ideal amount of lead in the human body is nil.. even tiny doses of lead can have adverse health consequences for infants and children."