Start with the cleanest source you can: sealed bottled water, then boiled mains water if it is still flowing. Rainwater from a clean roof can be collected in food-grade containers, but always treat uncertain water before drinking.
Basic storage
Use containers labelled for food use, wash them with soap, rinse well, and keep them out of direct sunlight. Rotate stored water every six months where possible.
Simple treatment
- Boil rolling for at least one minute (longer at altitude).
- Use an approved filter plus disinfectant for cloudy water.
- Never drink water with chemical sheen, strong odour, or unknown contamination.