The official government line is that NO amount of lead is safe to consume.
For the most part this is a non-issue because years of hard water scale have built-up on the inside of these lead pipes, so the water no longer makes direct contact with the lead.
The chemistry change in Flint caused corrosion, which undid this.
That’s an impossible target. I used to live about 30 miles northeast of flint, and the biggest issue with lake and well water was high levels of arsenic. I know where flint gets its water from. Their old water system is steel and cast iron piping, and about the only lead present would be in caulking at the joints.
Flint isn’t old enough to even consider having any real lead piping. I’ve done remodeling work on old houses in cities all along that stretch of I-75, and I have NEVER come across a single piece of pipe made out of lead.
About the only lead bearing material that I’ve came across is caulked joints in cast iron pipe, solder joints, and maybe some leaded brass fittings and fixtures. Not enough to be an issue.