How Cities Made Drinking Water Safe
Turn on a tap in most cities today and you can drink what comes out. That is one of the newest things about modern life. This video follows how cities got there.
In the early nineteenth century, London's water companies pumped from the same river its sewers emptied into. In 1829 James Simpson built a sand filter for the Chelsea Waterworks Company to make the water look cleaner. In 1854 John Snow traced a cholera outbreak that killed 420 people to a single pump on Broad Street, and showed that households drinking the Southwark and Vauxhall company's water died at fourteen times the rate of their neighbours. In 1892 cholera killed 8,605 people in Hamburg, while Altona next door, drinking filtered water from the same river, saw only a handful of cases.
Then chlorine: Maidstone in 1897, Lincoln in 1905, and on 26 September 1908 the Boonton Reservoir serving Jersey City, the first continuously chlorinated municipal supply in the United States. We explain what a modern treatment plant does, step by step: coagulation, flocculation, sedimentation, filtration and disinfection.
And what still goes wrong. Milwaukee, 1993: an estimated 403,000 people ill from a parasite that got through the filters. Flint, 2014: water without corrosion control, dissolving lead from old pipes. The EPA's October 2024 rule to replace lead service lines within ten years, now challenged in court. PFAS limits of four parts per trillion, set in April 2024, and the May 2026 proposal to give systems until 2031. Finally, the WHO/UNICEF 2025 count: 2.1 billion people still without safely managed drinking water.
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Educational documentary. Not financial or investment advice.
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- WHO and UNICEF, '1 in 4 people globally still lack access to safe drinking water', news release, 26 August 2025 (who.int), and the JMP report 'Progress on household drinking water, sanitation and hygiene 2000-2024' - 2.1 billion; 106 million surface water; 961 million gained 2015-2024; 68% to 74%; rural 50% to 60%; urban about 83%.
- Institution of Civil Engineers, 'London's water supply and the introduction of sand filtration' (ice.org.uk); Wikipedia, 'Chelsea Waterworks Company' - James Simpson, 1829, about one acre, beds of brick, gravel and sand.
- Wikipedia, '1854 Broad Street cholera outbreak' - Snow's quote from the 1855 second edition; outbreak from 31 August 1854; handle removed 8 September 1854; 420 deaths; Southwark and Vauxhall mortality 14 times Lambeth; first published 1849.
- National Research Council, 'Drinking Water and Health', Historical Note (NCBI Bookshelf NBK234165) - Hamburg unfiltered, Altona filtered; NPR, 'What Hamburg's Missteps In 1892 Cholera Outbreak Can Teach Us', 6 May 2020 - more than 17,000 cases; 8,605 deaths; Altona sand filtration from 1859.
- Wikipedia, 'Water chlorination' - Maidstone 1897; Lincoln 1905; Boonton Reservoir 1908, Leal and Fuller. Wikipedia, 'John L. Leal' and 'Boonton Reservoir' - 26 September 1908.
- MacKenzie et al., New England Journal of Medicine, 21 July 1994 - an estimated 403,000 ill; Corso et al., CDC Emerging Infectious Diseases 9(4), April 2003; Encyclopedia of Milwaukee (UWM) - about 4,400 hospitalised, at least 69 deaths.
- History.com, 'The Flint water crisis begins', 25 April; NRDC, 'Flint Water Crisis: Everything You Need to Know' - the switch on 25 April 2014, no corrosion control, return to Detroit water October 2015, nearly 100,000 residents exposed.
- US EPA, 'Lead and Copper Rule Improvements' (epa.gov), final rule 8 October 2024 - replace lead service lines within 10 years; AWWA article on the final rule - action level 15 to 10 ppb. NRDC case page, 'American Water Works Association v. EPA' - challenge in the D.C. Circuit, undecided.
- US EPA, 'Proposed PFOA and PFOS Compliance Extension Rule' and Federal Register 2026-10086, 20 May 2026 - MCLs of 4.0 ppt unchanged; compliance 26 April 2029 to 26 April 2031 for systems that request it; initial monitoring by April 2027; proposed rescission for PFHxS, PFNA and HFPO-DA.
Not regulated financial advice.