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How does contaminated drinking water spread cholera?

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Diagram of a water treatment plant showing the process from water inlet through mixing, coagulation, flocculation, settling, filtering, chemical treatment with chlorine, storage, and high-lift pumping to the distribution system. — water purification Water from inlets located in the water supply, such as a lake, is sent to be mixed, coagulated, and flocculated and is then sent to the waterworks for purification by filtering and chemical treatment. After being treated, the water is pumped into water mains for storage or distribution.

Cholera is an intestinal disease caused by the bacterium Vibrio cholerae, which spreads through the fecal-oral route. The disease is the archetype of waterborne illnesses, primarily transmitted when feces containing the bacteria contaminate water supplies that are subsequently ingested.12

Once the bacteria enter the intestine, they secrete an enterotoxin that disrupts the cellular mechanisms regulating fluid and electrolyte balance. This causes the intestinal lining to release massive quantities of fluid, leading to the severe watery diarrhea characteristic of the disease. Because infected individuals—including those with mild or no symptoms—shed the bacteria in their stool, they can easily contaminate local water sources, perpetuating the cycle of transmission.21

Ensuring a safe, clean supply of water is the fundamental requirement for preventing the spread of cholera. Effective public health interventions include the chlorination of water supplies, the use of narrow-necked storage containers to prevent recontamination, and the hygienic disposal of human waste to keep sewage from entering drinking water sources.3