Rome's lead water pipes were lined with protective mineral scale
Plumbing takes its name from plumbum, Latin for lead, because Roman pipes were made of it. Surprisingly, their aqueducts seldom poisoned anyone: the water was so rich in calcium that a crust of scale coated the pipe walls and kept water off the metal. Romans absorbed plenty of lead anyway, through cookware and wine preserved with lead.
Piped water and drainage began with cities large enough to need them. Mesopotamians laid clay sewer pipes around 4000 BCE, with early examples at Nippur and Eshnunna, and Uruk had brick latrines sitting on linked fired-clay drains by about 3200 BCE. The Hittite capital Hattusa used pipe sections that could be pulled apart for cleaning. By 2700 BC Indus Valley towns had standardised earthenware pipes with broad flanges sealed with asphalt, and around 2400 BCE a copper waste pipe connected Egypt's Pyramid of Sahure to its temple.
Rome marked the early peak, with vast aqueducts, tiled drains and lead pipes stamped with their owners' names to deter people from stealing water. After the empire fell, water supply and sanitation stalled or went backwards for more than a thousand years, with waste commonly dumped on the ground or into rivers. There were bright spots: wealthy households on the East African island of Kilwa enjoyed indoor plumbing in their stone houses around the 15th century. Real change came only with the crowded cities of the 1800s, when health officials pushed for underground sewers and separate water mains to curb epidemics.
Materials changed many times. London in the 16th and 17th centuries ran water through hollowed logs, tapered at one end and sealed with hot animal fat, and Philadelphia, Boston and Montreal did the same into the 1800s. Even during the Second World War, around 100,000 feet of built-up wooden pipe went into American culverts and storm drains. Galvanized iron was the usual American supply pipe from the late 1800s until about 1960, when copper took over, and awareness of lead poisoning after the war drove lead out of drinking water lines, though many old homes still have them.
Modern trade details are finer than they look. Pipes are cast or welded and usually thicker, while tubes are extruded with thinner walls. Copper tube comes in grades from thin type M to thick type K, yet all share the same outer diameter, so a thicker wall slightly narrows the flow.
Source: Plumbing
