Pompeii’s public baths were unhygienic until the Romans took over

A trip to Pompeii’s public baths meant taking a dip in water contaminated with sweat and urine – until the Romans took over and sanitation improved.

It’s easy to think of ancient Pompeii as a typical Roman city, particularly given that it lies only around 240 kilometres to the south-east of Rome itself. But for a large chunk of its history, Pompeii was occupied by the Samnite people, who had a distinct culture. It was only after 80 BC that it became a Roman colony, just 160 years before the city was buried under volcanic ash when the nearby Mount Vesuvius erupted.

Like the Romans, however, the Samnites seem to have been keen on bathing. They built at least two public baths – now known as the Stabian Baths and the Republican Baths – sometime after 130 BC.

Gül Sürmelihindi at the University of Mainz in Germany and her colleagues have now analysed mineral deposits in the bathhouses to gain a clearer insight into the quality of the water that once filled their bathing pools.

It turns out that the water quality could have been better. “Water in the hot pool of the Republican Baths had low stable carbon isotope values, indicating the presence of abundant organic matter,” says Sürmelihindi.

Significantly, when the researchers analysed mineral deposits in the 40-metre-deep wells that fed the pools, they found little sign of organic matter. “It means that the contamination must have taken place in the pools,” Sürmelihindi says – almost certainly from sweat, oily sebum produced by the skin, and even urine left by the bathers.

There’s probably a good reason for this, according to the researchers. Pulling water from the deep wells using a system of buckets was slow and laborious work, and they estimate that only between 900 and 5000 litres could have been drawn each hour. This was enough to replenish the water in the baths just once or twice per day.

But things changed under Roman rule. Within a few decades, the Romans had built an aqueduct to supply Pompeii with water from natural springs about 35 km to the north-east of the town. “We have the impression that building an aqueduct was a priority, but also a matter of prestige: if one city had one, the other would also want one,” says Sürmelihindi.

The researchers estimate that the aqueduct supplied Pompeii with 167,000 litres of water each hour – enough to replenish the public baths far more frequently, as well as provide Pompeii’s residents with a new and convenient supply of drinking water.

In line with the idea that public bathing became more hygienic, Sürmelihindi and her colleagues found that mineral deposits in the Roman-era drains from the Stabian Baths contained much less organic carbon, suggesting that any sweat and urine in the water was present at a much lower level because of more frequent replenishing of the bathing pools.

However, this doesn’t necessarily mean that Pompeiians enjoyed a health boost from the new aqueduct. Before its construction, most people drank rainwater collected in tanks connected to the roofs of the city’s buildings. Afterwards, many got their drinking water from the aqueduct via a network of lead pipes that ran through the city. Lead, a poison that can damage the brain, could then leach from the pipes and into the water.

The contamination should have lessened over time, because mineral deposits eventually coat the inside of the pipes so that the water is no longer in contact with the lead. But some researchers suspect that whenever sections of the city’s plumbing were repaired with fresh piping, lead contamination would spike again.

“Pompeii’s elite were probably better off, since they lived in houses with large atria with inward-sloping roofs that funnelled rainwater into a cistern,” says Duncan Keenan-Jones at the University of Manchester, UK. “Poor people who may have lived in their shops were more reliant on the lead-contaminated water from streetside fountains.”

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