I get your concern but it's quite unlikely that you get lead poisoning from solder. It's sufficient to let the water run for a while to be sure that any dangerous levels of lead are gone. Water has to be stagnant in full lead pipes for a certain time to be contaminating your water.
But yeah, better safe than sorry. I'm not sure about building codes around there but maybe you could escalate your concerns so this can be looked at by an expert?