How does contaminated water cause cholera?

Water becomes unsafe when sewage or stool enters a supply, storage vessel, well, river, or food-preparation area. The water may still look, smell, and taste normal. It can contaminate ice, drinks, uncooked food, and utensils, giving bacteria several ways to reach the mouth.

After swallowing the bacteria, a person may develop sudden watery diarrhoea and vomiting. These symptoms can remove fluid and salts rapidly. Exposure is more likely where sanitation is disrupted, during flooding or infrastructure failures, or when many people depend on a shared source that has not been safely treated.

Follow local public-health instructions about a water source. Use sealed bottled water or water treated by a reliable method for drinking, cooking, brushing teeth, making ice, and preparing oral rehydration solution. Keep treated water in a clean covered container and avoid dipping unwashed cups or hands into it.

Wash hands with soap and use safe water to clean food and utensils. If watery diarrhoea begins, take oral rehydration therapy according to its instructions and obtain medical advice. Severe dehydration or inability to drink may require IV fluid therapy. See the diarrhoea, oral rehydration therapy, and IV fluid therapy pages.

Seek urgent medical care for repeated watery stools, vomiting that prevents drinking, intense thirst, dizziness, fainting, confusion, marked weakness, or very little urine. Do not wait for a water test if symptoms are severe. Tell the clinician that contaminated water may have been involved and whether others used the same source.

Ask whether your water treatment method is adequate, how long to avoid the suspected source, how to protect household members, and how to mix and use oral rehydration solution. Ask which changes in urine, alertness, or thirst should prompt immediate reassessment.