New evidence about hygiene conditions in ancient Pompeii has come to light through a scientific study based on the analysis of limescale deposits found in wells, pipes, and bathhouse walls of the city, which was destroyed in 79 AD by the eruption of Mount Vesuvius.

According to the study, Pompeii’s earliest public baths did not meet the high hygiene standards usually attributed to Roman civilization. As explained by the lead researcher, Dr. Gul Surmelihindi of Johannes Gutenberg University, the water in the baths was repeatedly recycled, resulting in contamination from sweat, body oils, urine, and other organic residues.

According to gbnews.com, the researchers focused on the so-called Republican Baths, which were built in the 2nd century BC, during the Republican period. These baths continued operating into the early 1st century AD.

A decisive role in the research was played by carbonate limescale deposits, which form in layers over time, similar to tree rings. These layers trap carbon atoms, recording when organic materials entered the water supply system.

Human waste leaves a characteristic chemical “fingerprint,” allowing scientists to reconstruct water quality conditions.

Pompeii had no nearby river and for centuries relied on wells deeper than 30 meters. Slaves used wheel-based mechanisms to draw up water, a labor-intensive process that significantly limited the amount of water available.

As a result, the baths could refresh their water, at best, once per day—while in some cases this occurred only every two days.

Analyses revealed major differences in carbon isotopes between wells, reservoirs, and sewers, with the latter showing the highest levels of pollution. Scientists attribute this to the accumulation of human waste and the microorganisms that developed within it.

At the same time, risks from lead were identified, since water was transported through lead pipes. However, over time, mineral deposits built up inside the pipes, limiting the leaching of the metal into the water.

The situation improved significantly in the 1st century AD, when Emperor Augustus connected Pompeii to a large Roman aqueduct. The system carried clean water from the Apennine Mountains, using gravity instead of human labor, dramatically increasing water supply.

The more recent limescale deposits from this period are thinner and show different chemical characteristics, with far fewer indications of organic contamination—evidence that confirms the improvement in hygiene within the ancient city’s water system.