“While a harsh national spotlight focuses on the drinking water crisis in Flint, Mich., a USA TODAY NETWORK investigation has identified almost 2,000 additional water systems spanning all 50 states where testing has shown excessive levels of lead contamination over the past four years. The water systems, which reported lead levels exceeding Environmental Protection Agency standards, collectively supply water to 6 million people. About 350 of those systems provide drinking water to schools or day cares. The USA TODAY NETWORK investigation also found at least 180 of the water systems failed to notify consumers about the high lead levels as federal rules require…In all, the USA TODAY NETWORK analysis of EPA enforcement data identified 600 water systems in which tests at some taps showed lead levels topping 40 parts per billion (ppb), which is more than double the EPA’s action level limit. While experts caution Flint is an extreme case of pervasive contamination, those lead levels rival the 400-plus of the worst samples in far more extensive testing of around 15,000 taps across Flint. The 40 ppb mark also stands as a threshold that the EPA once labeled on its website an “imminent” health threat for pregnant women and young children.”