Common errors about Antiquity

[Epictetus]

I thought it was now accepted wisdom that the Romans knew lead was poisonous and for that reason did not make wide spread use it in their plumbing.

Vitruvius seems to have known it was dangerous and specifically recommends against it.

water from clay pipes is much more wholesome than that which is conducted through lead pipes, because lead is found to be harmful for the reason that white lead is derived from it, and this is said to be hurtful to the human system. Hence, if what is produced from it is harmful, no doubt the thing itself is not wholesome.

This we can exemplify from plumbers, since in them the natural colour of the body is replaced by a deep pallor. For when lead is smelted in casting, the fumes from it settle upon their members, and day after day burn out and take away all the virtues of the blood from their limbs. Hence, water ought by no means to be conducted in lead pipes, if we want to have it wholesome.

Vitruvius, VI.