Ancient Rome’s lead plumbing was an architectural marvel, connecting the expansive republic and its vast population to a steady water supply brought in through aqueducts and flushing waste out through cavernous sewers (like the Cloaca Maxima, above). Written records for the construction of this plumbing system are sparse, but a new study suggests sediment layers near the pipes’ outflow are contaminated with history. Researchers drilled out 177 core samples from the port of an ancient Roman harbor town called Ostia, southwest of the main city. They used radiocarbon dating to gauge each sediment layer’s age, then analyzed the layers for their chemical content. They found a large spike in the concentration of lead around 200 B.C.E., indicating the lead pipes were installed around this time, the researchers report today in the Proceedings of the National Academy of Sciences. That’s about 150 years older than the earliest known archaeological evidence for lead plumbing in ancient Rome. A hundred years later in the sedimentary record, the scientists noted a drop in lead levels, implying a breakdown in the system. The timeline aligns with Roman civil wars throughout the first century B.C.E. that would have led to neglect. Previous studies have suggested these pipes might have contributed to lead poisoning in the ancient world. This new study raises the possibility that outflow from the pipes might have contaminated the harbor water with lead, as well, potentially poisoning fish and other sea life.