The effects are cumulative. It's not the same for someone who goes to Flint and has a glass of water as it is for people who drink several glasses a day of it for years.
A) The entire thing is that Flint decided to no longer subsidize Detroit's water system and went to the river as a source. Liberals hate it when liberals don't follow what they're told to do, hence the 'crisis.'
B) It is Flint Michigan - most of the houseses are older construction, environmental lead is one of the highest in the nation. In the 'danger' homes, the highest recorded lead levels were 15 ppb, but that appears to be tainted by the home - a second test at the water main showed 4 ppb.
Again, this is an invented catastrophe. Oh, and for comparison, 57% of the tested taps in Washington DC are over 5 ppb, but I'm pretty sure we're not doing water bottle drops into the capitol.