gnu,
My co-op in NYC had to do major plumbing to comply with NYC lead regulations. But to our surprise, the levels in two buildings were still high. Why? Because the city's side of the connection was lead and they were under no obligation to change it NOR COULD WE.
So we ran water in the morning and flushed toilets to get any water that had been standing overnight through the system.
BIG SIGH.
SINS