TechnologyEurope
Sewers and clean water
Probably what has saved the most lives in the history of cities
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Snow's map of Broad Street is among the most famous in the history of science and is reckoned the birth of epidemiology. Treatment works and water chlorination brought larger falls in mortality in many cities than any medicine. Half the world's population gained access to safe sanitation only in the twenty-first century.
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When the Thames smelled so foul in the summer of 1858 that parliament could not sit, they voted money for a sewer system for London. John Snow had already shown that cholera came from water rather than air, by mapping deaths around a single pump.
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Part of Terra Saga — the story of Earth on a timeline. terrasaga.org