Pretty much any older building has lead pipes carrying the water supply. It is only a problem if something disrupts the buildup of scale that insulates the lead from the water.
This could vary from street to street or even house to house.
Lead pipes? I mean, potable water systems where the pipes are actually made out of solid lead metal?
I have never seen ANY plumbing anywhere that has pipe made from actual lead. Solder joints on copper pipe, yes. Caulking on old cast iron DWV pipe, yes.
This is like the arsenic in the groundwater in Michigan. It occurs naturally, nobody put it their. The threshold levels set by the DEQ are ridiculously low. You would have to drink like a million gallons to have any sort of adverse effect.
Century-old water pipes should have been replaced decades ago, but the fiscal realities have precluded that in many neighborhoods.
Detroit has been fortunate in that much of its older housing stock has been largely demolished or is presently uninhabitable.