Lead-contaminated water is not unique to Flint, Mich., or Newark, N.J., where excessively high levels of lead contaminate drinking water. Millions of Americans may unknowingly be drinking water contaminated with lead, either because of old lead pipes or from faucets and other plumbing fixtures with high levels of lead. Lead is especially dangerous for children, and its devastating harm can last a lifetime.   Scientists, including the Centers for Disease Control and Prevention, agree that any amount of lead in the blood during childhood is harmful. Children are particularly vulnerable during the first six years of life, because their brains are in critical stages of development. Even tiny amounts of lead in kids’ bodies are harmful. Lead exposure can alter a child’s behavior, ability to concentrate, memory and learning. Moreover, the harmful effects of exposure are irreversible and can continue well into adulthood. The American Academy of Pediatrics has recommended that drinking water given to children contain no more than 1 part per billion, or ppb, of lead. Children are commonly exposed to lead in dust or soil contaminated with lead paint, but drinking water can also be a signi...