Collecting and purifying rainwater
Machine translation from Dutch, not yet checked by a clinician.
In an emergency rainwater can be collected as a source of drinking water, but it always needs purifying.
What to do
• Collect rainwater in clean buckets or barrels on a clean surface
• Avoid collecting water from roofing with rust, tar or a chemical coating
• Filter the water through a clean cloth to remove coarse particles
• Boil the water for 1 minute before drinking it
• Store it in clean sealed containers and refresh after 24 hours at most
Do not do
• Do not use water collected from roofs containing asbestos
• Do not store collected rainwater for longer than 24 hours without cooling
• Do not drink the water unboiled
Warning signs
• The water has an odd colour, smell or foam — do not use it
• The water was collected during a chemical incident or a nearby fire — do not use it
Get help if
• There is no way to boil or filter water
• No clean collecting containers are available
Why this matters
Rainwater is in principle free of bacteria but can carry air pollution. Boiling removes the biological risks.
Source: WHO Rainwater Harvesting Guidelines · reviewed 2025-01-01