Rome’s Amazing Public Water Systems

another public fountain in pompeii | Jennifer Smith | Flickr

Roman public fountain

Lecture 14: Go With the Flow – Urban Water Distribution

Understanding Greek and Roman Technology: From the Catapult to the Pantheon

Dr Stephen Ressler (2013)

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Many former Roman cities still have partial remains of their public water systems (eg basins, water channels, clay pipes and public toilets. Nearly all the metal fixtures (lead pipes, iron fasteners and bronze faucets) are gone, having been recycled. However the public water system in Pompeii (buried by volcanic eruption in 79 AD) has survived intact. Historians also have a good description of Rome’s public water system in De Aquaducur, written by Rome’s water commissioner Sextus Julius Frontinus in 97 AD.

All Roman cities had gravity-based continuous flow water systems. From the aqueduct, water flowed into two sequential settling tanks to remove sand, silt and other suspended solids. It there it went to constellum divisorum, which divided the flow into separate pipes (lead, favored to its low melting point) headed to public fountains (the primary water source for most residents), the public baths and private homes (about 10%).

Plumbarii* produced the lead pipes by pouring molten lead into a horizontal cooling tray and shaping it around a cylindrical wooden form. They then soldered the seams together with a lead-tin alloy with an even lower melting point.

Paying their own plumbarii to attach a bronze fitting called a calyx to the water main to deliver water to their private homes, the wealthy elite mounted the delivery pipes (at times made of silver) on their interior walls as a status symbol. The pipes emptied into a centrally located basin, with the overflow channeled to the sewer system. It often traveled through their garden, where it was used for irrigation.

Fountains were usually located at the base of a 20-foot tall constellum, which, like a modern water tower, functioned as a reverse siphon (reducing water pressure for downhill users). Pompeii had 50 fountains, spaced roughly 300 feet apart. Most were rectangular stone basins held together with clamps. Fountain overflow ran down the streets (as a form of street cleaning) to be collected by the sewers.

Water directed to public toilets was usually waste water from the public baths. It entered the toilets via two channels, one beneath the toilet seats to carry away wastes and one in from of the seats for hand washing. Both emptied into the sewer system.

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Both rain and waste water entered the masonry sewers through openings in the street pavement. The sewers emptied into larger collector channels, which emptied into a single great sewer that emptied into the river. Rome’s main sewer, the Cloaca Maxima, still operates today.

However most people emptied their waste directly into the street. Pompei had tall stepping stones across many of their streets to enable people to keep their feet dry. Gaps between stones allowed vehicles to pass.

Pompeii, Italy. Raised stepping stones across the cobbled street at Stock Photo, Royalty Free ...