The ancient Roman plumbing system was a legendary achievement in civil engineering, bringing fresh water to urbanites from hundreds of kilometers away. Wealthy Romans had hot and cold running water, as well as a sewage system that whisked waste away. Then, about 2200 years ago, the waterworks got an upgrade: the discovery of lead pipes (called fistulae in Latin) meant the entire system could be expanded dramatically. The city’s infatuation with lead pipes led to the popular (and disputed) theory that Rome fell due to lead poisoning. Now, a new study reveals that the city’s lead plumbing infrastructure was at its biggest and most complicated during the centuries leading up to the empire’s peak.
Hugo Delile, an archaeologist with France’s National Center for Scientific Research, worked with a team to analyze lead content in 12-meter soil cores taken from Rome’s two harbors: the ancient Ostia (now 3km inland) and the artificially-created Portus. In a recent paper for Proceedings of the National Academy of Science, the researchers explain how water gushing through Rome’s pipes picked up lead particles. Runoff from Rome’s plumbing system was dumped into the Tiber River, whose waters passed through both harbors. But the lead particles quickly sank in the less turbulent harbor waters, so Delile and his team hypothesized that depositional layers of lead in the soil cores would correlate to a more extensive network of lead pipes.
Put simply: more lead in a layer would mean more water flowing through lead pipes. Though this lead probably didn’t harm ocean wildlife, it did leave a clear signature behind.