Switching water sources improved hygiene of Pompeii’s public baths
From well to aqueduct
Specific sites studied included the Stabian Baths and associated structures, which were built after 130 BCE and remained active until the aforementioned eruption; the Republican baths, built at the same time but abandoned around 30 BCE; the Forum Baths, built after 80 BCE; and the aqueduct and its 14 water towers, built in the Augustan era.
The women’s hot bath, or caldarium, of the Stabian baths of Pompeii.
Cees Passchier
The women’s hot bath, or caldarium, of the Stabian baths of Pompeii.
Cees Passchier
Water lifting installations in the seaside installations studied.
Gül Sürmelihindi et al., 2026
Water lifting installations in the seaside installations studied.
Gül Sürmelihindi et al., 2026
The women’s hot bath, or caldarium, of the Stabian baths of Pompeii.
Cees Passchier
Water lifting installations in the seaside installations studied.
Gül Sürmelihindi et al., 2026
Variations in the chemical composition of the deposits were noted, indicating the replacement of boilers to heat water and renewal of water pipes in Pompeii’s infrastructure, particularly around the time modifications were being made to the Republican Baths. Results from heated swimming pools at the Republican Baths, for example, showed clear contamination by human activity, particularly by human waste (sweat, sebum, urine or bath oil), suggesting that the water was not changed regularly.
This is consistent with the limitations of the water supply at the time; the water-lifting machines could actually only refresh the water about once a day. After the well was enlarged, the carbonate deposits were much thinner, evidence of technological improvements that reduced sloshing as the water rose. Once the aqueduct was built, bathing facilities were expanded, probably with a corresponding improvement in hygiene.
Overall, the aqueduct represented a net benefit to Pompeii. “Changes in the water supply system of Pompeii revealed by carbonate deposits show a shift from a well supply to an aqueduct with an increase in the volume of water available and the size of bathing facilities, and probably an increase in hygiene,” the authors conclude. Certainly there was evidence of lead contamination of water, particularly that supplied by the aqueduct, but carbonate deposits in lead pipes appear to have reduced these levels over time.
The results may also help resolve a scientific debate about the origins of the aqueduct’s water: was it water from the town of Avella connected to the Aqua Augusta aqueduct or from the Pompeii wells/Vesuvius springs? According to the authors, the stable isotopic composition of carbonate in the aqueduct is not consistent with carbonate from volcanic rock sources, thus supporting the Avella Spring hypothesis.
PNAS, 2025. DOI: 10.1073/pnas.2517276122 (About DOIs).
