33 cities in the US have been found to have cheats built into their lead-testing policies. The water that leaves your local treatment plant is rigorously tested and may well be perfectly suitable for consumption. Its the infrastructure that delivers the water to your home which is the issue. Cities that have aging lead pipes have two options for dealing with them: Replace them, or treat the water running through them with anti-corrosives that prevent the pipes from breaking down. Even if you don’t have lead pipes, tiny pieces of lead solder or lead rust still might make their way into your water.”]
Source: https://gizmodo.com/protect-your-drinking-water-from-lead-is-more-important-1780873082