For roof rain plus river water, the CDC's steps are: let it settle and pour off the clear part, or filter it through a clean cloth or coffee filter. Then bring it to a rolling boil for 1 minute (3 minutes above about 2,000 m). Boiling kills germs. It doesn't remove silt, and it doesn't remove chemicals: anything washed off the roof, or upstream runoff in the river water, stays in. So if it's only brown from silt, settle it, filter it and boil it, and the coffee should be fine. If it smells of fuel or anything chemical, skip it.

Water, Sanitation, and Hygiene (WASH)-related Emergencies and Outbreaks

How to Make Water Safe in an Emergency

After an emergency, you may not have safe tap water. Use bottled, boiled, or treated water instead.

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