Earlier quoted context omitted.
The lead pipes theory is mostly just pop-science. Romans were likely getting more lead exposure from using lead cooking vessels and utensils.
also lead flavoring lead tastes sweet, sugar wasn't cheaply & widely available, honey is expensive etc. and knowledge about lead poisoning was not really a think AFIK at the same time lead pipes tend to gain a crust of chalk over time (depending on chalk content of the water) which mostly defuses their danger. Like you will find some very old houses with lead tape water pipes in the EU today but if you test their tap…
Of course, him mentioning "Don't do this" suggests that lead water pipes into the home were common enough to need a warning against.