What happens when boiling it twice?

For your morning coffee, because you forgot the well on the stove ... the reason is the least, many have the habit of boiling water twice or more, without noticing that this habit puts our health at risk.

According to Environmental Protection Agency, United States, Much of the amount of drinking water consumed has elements that contribute to rashes and burns on the skin, erosion of tooth enamel and intoxication, for example, lead.