“Lead free” isn’t zero lead.
> In 1986, Congress amended the Safe Drinking Water Act (SDWA), prohibiting the use of lead in pipes, and solder and flux on products used in public water systems that provide water for human consumption. Lead-free was defined as solder and flux with no more than 0.2% lead and pipes with no more than 8%.
> In 2011, Congress passed the RLDWA, which revised the definition of lead free and took effect in 2013. Lead free was now defined as the lead content of the wetted surfaces of plumbing products as a weighted average of no greater than 0.25% for products that contact water intended for consumption, and 0.2% for solder and flux.
https://www.workingpressuremag.com/epa-final-lead-free-rulin...
A lot of municipal water systems have done more recent (but by no means required) improvements to the water itself to “coat” the lead in supply lines. Beyond just pH control, like orthophosphate. Most just in the last decade or so.
For Chicago, it’s an active project
> Polyphosphate is being removed because recent studies have shown that it may
negatively impact lead corrosion control.
> Polyphosphate was initially added with the orthophosphate to mask discoloration of the water from metals such as iron or manganese.
https://villageofalsip.org/Chicago%20Department%20of%20Water...