Implying that the river water was contaminated is misleading. The river water was perfectly capable of being used as drinking water if treated properly, but they didn't and so the pipes were damaged by acidic water which contaminated the drinking water with lead.
It's totally fair to have a distrust of public officials after something like this, but they're not the same officials, and the water has been tested by independent parties.
It's not really in doubt that the pipes have been replaced. It's not something you can do that people might miss. They very obviously dug up and replaced a lot of pipes.