If your child isn't doing too well at school, check out the water supplied to your home. Deposits of manganese, a metal, in your water will have a dramatic effect on your child's mental capacities. Even low levels of the metal have a significant impact on a child's intelligence level and ability to learn, a new study has discovered. The study, which included 362 children in Quebec, Canada, found that IQ levels were significantly lower in those children whose homes had manganese in the drinking water. Even low levels of the metal - far below levels currently considered dangerous - affected the children. On average, children who were drinking manganese had an IQ rating that was six points below those who were not exposed to the metal in their water. (Source: Environmental Health Perspectives, September 21, 2010; doi: 10.1289/ehp.1002321).