Government or official record
1993 Cryptosporidium Outbreak
Milwaukee Water Works
Where this source supports the record
Each entry separates the article’s editorial relevance note from its exact, section-level claims. A bibliography link without a direct claim is labeled plainly.
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Epidemics & public health · March–April 1993Open article references →
The Milwaukee Cryptosporidium Outbreak
Howard Avenue Water Purification Plant service area · United States
Why editors use it hereUtility history of operations, response, upgrades, and present safeguards.
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Quick read
In spring 1993, the parasite Cryptosporidium passed through Milwaukee's southern water-treatment plant and caused the largest documented waterborne disease outbreak in United States history.
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Trigger and conditions
In late March, changing lake conditions and treatment performance produced elevated turbidity in finished water, but the signal did not immediately trigger a shutdown.
Reviewed 26 July 2026 -
Uncertainty
The estimate of 403,000 illnesses comes from population surveys, not individual laboratory confirmation.
Reviewed 26 July 2026 -
Why it matters
The outbreak shows how a treatment plant can meet familiar microbial assumptions yet fail against a chlorine-resistant organism.
Reviewed 26 July 2026
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Quick read