How to Convert Rain Water to Drinking Water

by Christopher Donahue

Rainwater is generally pure water and is safe to drink if you collect it in a clean container. Water found while camping may have rainwater as its source but is susceptible to contamination as soon as it hits the ground. There are several simple methods to convert collected rainwater into safe drinking water. After purification, pour the water into a clean glass or jar to avoid contaminating your results.

Boiling

1. Remove rainwater from the top of your collecting tub. Allow the rainwater remaining in the tub at least an hour to settle out heavy particles. Avoid stirring up the settled particles as you draw water out. Pour the clear water into the 1-quart metal pan.

2. Start a fire using dry firewood and matches.

3. Heat the covered metal pan holding the rainwater, bringing the water to a boil for 10 to 15 minutes.

4. Allow the water to cool before drinking. This is the most certain method to purify rainwater (or river, lake or stream water) by killing waterborne pathogens (disease-causing organisms).

Chemical Purification

1. Repeat step 1 from the "Boiling" section to place clear rainwater into the metal pan.

2. Add 4 to 6 drops of liquid chlorine bleach to the 1 quart of rainwater. If the pot is larger, increase the number of drops of chlorine at the 4 to 6 drops per quart rate.

3. Allow at least 30 minutes for the chlorine to disinfect your water if the water is 70 degrees F or above. Allow up to an hour if the water is near freezing.

4. Add iodine to the water from step 1 of this section if chlorine is not available. Add it at 3 to 5 drops per quart of water to be treated and allow at least 20 minutes of disinfection time at 70 degrees F.

5. Mix the iodine-treated water with powdered flavoring crystals (such as orange fruit drink) if available as iodine-treated water has an unpleasant taste.

Solar Pasteurization

1. Fill a 1-quart clear ziplock bag with water as in step 1 of the "Boiling" section.

2. Spread at least 2 feet of heavy-duty aluminum foil with the shiny side up.

3. Place the freezer bag flat onto the foil in a location with maximum direct sunlight.

4. Place additional aluminum foil around the laid-out freezer bag to form a bowl reflecting additional solar energy toward the bag, if practical.

5. Allow the bag to heat for several hours. Note: The water does not need to boil. Bringing the water to 160 degrees F or greater for several hours, as well as the sterilizing effects of the ultraviolet rays of the sun, will kill waterborne pathogens.

Items you will need

  • Rainwater
  • 1 gallon (or larger) clean plastic bucket or tub
  • 1-quart (or larger) black metal pan with lid
  • Firewood
  • Matches
  • Liquid chlorine bleach (no additives)
  • 2% tincture of iodine
  • Powdered flavoring crystals (such as orange fruit drink) (optional)
  • Quart-size clear plastic ziplock bag
  • Heavy-duty aluminum foil
  • Clean glass or jar

Tip

  • Where possible, collect directly falling rainwater into the collection tub or funnel rainwater using clean plastic sheeting to direct additional rainwater to the tub.

Warnings

  • These purification techniques will kill waterborne pathogens. They will not remove toxic chemicals.
  • Water contaminated by chemicals should be avoided.

About the Author

Chris Donahue is an electrical engineer living in the Dallas area. He has worked on defense projects, semiconductor process equipment, instrumentation and is currently in water utilities. He earned his Registered Massage Therapist (RMT) standing in Texas in 1999.

Photo Credits

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