History of water supply and sanitation

• 1. Introduction

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  The history of water supply and sanitation begins with a well on the island of Cyprus, dug around 8500 BCE. That single pit in the earth represents a turning point: the moment when humans stopped wandering to find water and started engineering their world to bring it to them. From that moment forward, every city, every empire, every public health crisis has been shaped by one inescapable question. Can people get clean water in, and get waste out, reliably enough to survive?

  The stakes were never abstract. When systems failed, disease swept through populations. The Plague of Justinian in 541-542 CE and the Black Death between 1347 and 1351 killed tens of millions of people, with unsanitary conditions and overcrowding among the key drivers. Before Liverpool engineer James Newlands built his sewer network in the mid-19th century, life expectancy in that city stood at just 19 years.

  This is a story that spans nearly ten thousand years and every inhabited continent. It involves brilliant engineers, obstinate politicians, and the slow accumulation of understanding about what makes water deadly. The answers took millennia to arrive.

• 2. Ancient Foundations

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  At Nippur and Eshnunna in Mesopotamia, excavators found clay sewer pipes dating to around 4000 BCE, placed to carry wastewater away from buildings and capture rainwater in wells. These were not crude ditches. They were engineered components. At Uruk, brick-constructed latrines appeared as early as 3200 BCE. In the Hittite city of Hattusa, clay pipes came with detachable, replaceable segments specifically designed to allow cleaning.

  The Indus Valley civilization, flourishing in what is now Pakistan and India, took urban sanitation further than almost any society of its era. At the city of Lothal, the ruler's house had a private bathing platform and latrine connected directly to an open street drain that discharged into the town's dock. Other homes on the acropolis drained into covered brick sewers held together with gypsum-based mortar, running to soak pits outside the town walls. Lower-town residents used soak jars, large buried urns with a hole in the bottom, which were regularly emptied and cleaned. The city drew water from two wells, one on the acropolis and one at the dock.

  At Harappa and Mohenjo-daro, drains from individual houses connected to wider public drains running beneath major streets. Buildings at Mohenjo-daro often rose two or more stories; water from upper-floor bathrooms moved through enclosed terracotta pipes or open chutes that emptied onto street drains below. Ruins at Mohenjo-daro in Pakistan and Dholavira in Gujarat included drainage channels, rainwater harvesting, and street ducts.

  On the island of Crete, the Minoan civilization installed an inverted siphon system with glass-covered clay pipes in its palace at Knossos. That system, built around the 16th century BCE, was still in working order roughly 3,000 years later. The Minoans also constructed stone sewers regularly flushed clean by rainwater flowing through their collection networks, and devised elaborate heating systems alongside their water infrastructure.

• 3. Rome and the Islamic World

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  Rome's Cloaca Maxima, a sewer draining into the Tiber River, was considered a marvel of engineering in the ancient world. Public latrines were built directly over it. The Roman Empire ran indoor plumbing into homes and to public wells and fountains across its territory, using a system of aqueducts and pipes. A water wheel device called a noria supplied water to aqueducts and distribution systems in major cities across Europe and the Middle East.

  Roman Britain, occupied between 46 BCE and 410 CE, inherited this infrastructure. Towns and garrisons built complex water supply and sewer networks. Supply pipes were lead, wooden with iron-ring reinforcement, or hollowed logs jointed together. Stone-lined drains connected to sometimes massive sewer tunnels, such as those excavated at York. At the garrison serving Hadrian's Wall, latrines at Housesteads were flushed with collected rainwater and standing water.

  Across the medieval Islamic world, a different sanitation tradition took hold. In the Abbasid Caliphate, which spanned the 8th through 13th centuries, the capital city of Baghdad maintained 65,000 baths alongside a sewer system. Islamic hygienical jurisprudence, dating back to the 7th century, required ritual bathing and washing after using the toilet; the result was that cities built water supply systems delivering large quantities of water for ritual washing in mosques and hammams. Medieval cities including Baghdad, Cordoba, Fez, and Fustat developed sophisticated waste disposal and sewage networks. In Fustat, multi-storey tenement buildings up to six floors high had flush toilets connected to a water supply system, with flues on each floor carrying waste into underground channels.

  The scholar Al-Karaji wrote The Extraction of Hidden Waters, presenting groundbreaking descriptions of hydrological and hydrogeological concepts including components of the hydrological cycle, groundwater quality, and an early water filtration process. Not every account of Islamic sanitation was favorable, however. The Egyptian physician Ali ibn Ridwan wrote in the 11th century that residents of al-Fustat threw dead animals into the streets and that sewers emptied into the Nile, noting that when floodwaters receded people drank the resulting contaminated mixture. Later colonial commentary on Egyptian sanitation, such as a British doctor's 1883 report on Damietta, was characterized by historians writing in 2023 as reinforcing a colonial view of Egyptians as inferior to European colonisers.

• 4. Medieval Europe and Sewage as Gunpowder

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  Contrary to a persistent popular myth, bathing and sanitation were not abandoned in Europe after the fall of Rome. Public bathhouses remained common in medieval Christian cities including Constantinople, Paris, Regensburg, Rome, and Naples. Pope Gregory the Great urged followers to bathe as a bodily need. The Church built sex-segregated bathing facilities near monasteries and pilgrimage sites, and popes installed baths inside basilicas.

  Waste disposal was a separate and grimmer matter. In Paris, open gutters called kennels, or "split streets," ran wastewater down the center of roadways, physically dividing them in two. The first closed sewer constructed in Paris was designed by Hugues Aubird in 1370 on Rue Montmartre, built less to manage waste than to contain the stench from open channels. In Dubrovnik, then called Ragusa, the Statute of 1272 set out precise parameters for building septic tanks and channels for dirty water removal. A full sewage system was constructed throughout the 14th and 15th centuries and remains operational today.

  In the 16th century, Sir John Harington invented a flush toilet as a device for Queen Elizabeth I, his godmother, that released wastes into cesspools. One of the stranger turns in sanitation history followed shortly after the adoption of gunpowder in Europe. Municipal outhouses became strategically valuable as a raw source of saltpeter. In London, the contents of outhouses were collected nightly by commissioned wagons and delivered to nitrite beds, where the material was laid into specially designed soil beds to produce earth rich in mineral nitrates. That nitrate-rich earth was then processed into potassium nitrate, a key ingredient in black powder. Waste had become a military asset, carrying a supply chain that ran from city latrines directly to the manufacture of gunpowder.

• 5. The 19th Century Crisis

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  By 1802, Napoleon had built the Ourcq canal, delivering 70,000 cubic metres of water a day to Paris, while the Seine River received large quantities of wastewater daily. The cholera epidemic of 1832 in Paris sharpened public awareness that this arrangement was unsustainable. Between 1865 and 1920, Eugene Belgrand oversaw the construction of roughly 600 kilometres of aqueducts to bring potable spring water into the city; the displaced lower-quality water was redirected to flush streets and sewers. By 1894, laws required mandatory drainage. Even so, untreated Parisian sewage concentrated downstream in the town of Clichy to the point that residents were effectively forced to relocate.

  In Liverpool, James Newlands was appointed Borough Engineer on the 26th of January 1847. He conducted roughly 3,000 geodetical observations to build a precise contour map of the town, presented a comprehensive drainage plan to the Corporation in April 1848, and began construction in July 1848. Over the following 11 years, 86 miles of new sewers were built; a further 58 miles were added between 1856 and 1862. The programme finished in 1869. Before Newlands began, life expectancy in Liverpool was 19 years. By the time he retired, it had more than doubled.

  London's solution came partly through catastrophe. Cholera outbreaks struck in 1832, 1849, and 1855, each killing tens of thousands. The Great Stink of 1858, when untreated sewage in the River Thames became overpowering, finally forced Parliament to act. Civil engineer Joseph Bazalgette, Chief Engineer of the Metropolitan Board of Works, designed a network of six main interceptor sewers totaling almost 100 miles. Those sewers were fed by 450 miles of main sewers, which in turn drew from roughly 13,000 miles of smaller local pipes. Construction between 1859 and 1865 required 318 million bricks, 2.7 million cubic metres of excavated earth, and 670,000 cubic metres of concrete. Pumping stations at Chelsea, Deptford, and Abbey Mills raised sewage where gravity alone was insufficient. With minor modifications, Bazalgette's design remained the basis for sewerage engineering into the present day.

• 6. Clean Water and Chlorine

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  John Gibb, owner of a bleachery in Paisley, Scotland, installed an experimental sand filter for his water supply in 1804, then sold the filtered surplus to the public. That private experiment was refined over two decades. In 1829, engineer James Simpson installed the first treated public water supply in the world for the Chelsea Waterworks Company in London, providing filtered water for every resident of the area.

  The Metropolis Water Act later required that all London water be "effectually filtered" from the 31st of December 1855. Legislation for mandatory inspection of water quality, including chemical analyses, followed in 1858. That law set a precedent followed by governments across Europe.

  Chlorine arrived as the next advance. William Soper used chlorinated lime to treat sewage from typhoid patients in 1879. Moritz Traube formally proposed adding calcium hypochlorite to drinking water in a paper published in 1894; two other investigators confirmed his findings in 1895. The town of Maidstone in Kent became the first place to have its entire water supply treated with chlorine, in 1897. Permanent chlorination began in 1905 in Lincoln, England, after a faulty sand filter caused a serious typhoid epidemic. Dr. Alexander Cruickshank Houston used chlorination to stop that outbreak, and the treatment continued until 1911 when a new water supply was installed. In 1908, Boonton Reservoir on the Rockaway River, serving Jersey City, New Jersey, became the first continuous chlorination site in the United States, with doses of 0.2 to 0.35 parts per million. The treatment was conceived by Dr. John L. Leal and the plant was designed by George Warren Fuller.

  Water fluoridation followed a different path. Dr. H. Trendley Dean, head of the Dental Hygiene Unit at the National Institutes of Health, began investigating fluorosis in 1931. By the late 1930s, his team established that fluoride levels up to 1.0 ppm in drinking water did not cause enamel fluorosis in most people. In 1945, Grand Rapids, Michigan became the first city in the world to fluoridate its drinking water, following a vote by its City Commission the previous year.

• 7. Treating What Goes Out

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  Edward Frankland ran experiments at a sewage farm in Croydon, England, during the 1870s, demonstrating that passing sewage through porous gravel produced a nitrified effluent and kept the filter unclogged over long periods. William Dibdin, chief chemist for the London Metropolitan Board of Works, elaborated on this in 1887, describing a process of separating sludge, aerating the remaining liquid, and discharging a purified effluent. From 1885 to 1891, filters working on Dibdin's principle were built throughout Britain, and the Lawrence Experiment Station in Massachusetts confirmed Frankland's findings, developing a trickling filter in 1890 that gave more reliable performance.

  Contact beds, tanks packed with stones or slate to maximize surface area for microbial growth, were developed in Salford, Lancashire and by scientists working for the London City Council in the early 1890s. They were adopted in Leicester, Sheffield, Manchester, and Leeds. Joseph Corbett, as Borough Engineer in Salford, simultaneously developed the bacterial bed; 1905 experiments showed his method could purify greater volumes of sewage more effectively than contact beds.

  In 1912, the Royal Commission on Sewage Disposal published its eighth report establishing what became an international standard: the 20:30 standard, allowing 2 parts per hundred thousand of biochemical oxygen demand and 3 parts per hundred thousand of suspended solid in sewage discharged to rivers. That same year, scientists at the University of Manchester discovered the activated sludge process, which most Western cities then adopted for sewage treatment in the early 20th century.

  The precursor to the modern septic tank was invented by L.H. Mouras in France in the 1860s. Donald Cameron, City Surveyor for Exeter, patented an improved version in 1895, naming it a septic tank, with septic meaning bacterial. Septic tanks remain in worldwide use today, particularly in rural areas without large-scale sewer connections, a direct line of descent from Cameron's 1895 patent.