How to purify water for drinking

Something that you realize fast during any outdoor adventure or any disaster situation. Water weighs a LOT! 8.3 pounds per gallon adds up fast!

Emergency prep experts tell us to try to stockpile 1 gallon of water per person per day in the event of emergencies – and to be prepared to last out the first 72 hours of any emergency before help can arrive.  But 3 gallons of water (for 3 days) would put each person carrying more than 25 pounds (11 kg) of water.

The same estimates apply if you are hiking or backpacking or even canoeing – especially in hot weather.  On an outdoor adventure you can expect to need 1 gallon of drinking water per person per day.  But if you’re on the move, 8 pounds of water becomes onerous fast, and if you’re on a 4-day backpacking trek, you are certainly not going to drag 33 pounds of drinking water with you from home.

bc_water_1This is where planning and water purification come in handy.  Plan to be near a water source at least twice per day if possible, and be prepared with knowledge, skills, and gear you need to purify that water for drinking.

There are four basic ways to make water safe to drink

Bringing water to a rolling boil for 3 minutes is the gold standard for water purification.

I have seen each of the four above methods used successfully on long backpacking trips BUT the CDC recommends either boiling or a combination of any two of the other three methods (filtration+chemical or filtration+radiation).

A few hints for each of these water purification methods.

  • Boiling is most effective at killing pathogens and is handy for purifying large batches of water, but it takes a lot of time to boil the water for 3 minutes, then let it cool) and can use up a lot of fuel.
  • Boiling and chemical methods make the water taste bad.  This can be overcome by using flavor packets or in the case of boiling, simply shaking the water up in your bottle or pouring it from bottle to bottle to aerate the water.
  • If you are going to use liquid chlorine bleach (2 drops/quart) as a chemical disinfectant for drinking water, make SURE that it is plain-old regular bleach (nothing but sodium hypochorite and water) and not some scented product containing bleach because some of the stuff that is added to some bleach products can be toxic.
  • Radiation/UV light methods (obviously) involve technology and require batteries.  The other 3 methods are probably more reliable in the long run.
  • Boiling, chemical, and radiation methods can kill pathogens but they cannot remove chemical pollution or particulates – only filtration can do that.

My preferred procedure is as follows –

  1. Only use flowing water sources – avoid stagnant water.
  2. Pre-filter the water through a cheesecloth, a rag, or even the sleeve of your shirt to remove large particulates like sand and mud.
  3. Filter the water by forcing it through a microfilter like this one.
  4. Drop an chlorine tablet chlorine tablet into the bottle and shake it up.
  5. Add a packet of lemonade mix or crystallized lime to the cleaned water.  This will improve the taste and provide a tiny fraction of additional assurance by acidifying the water.
  • Follow the manufacturer instructions for both the filter and the chemical tablets.
  • Make sure you never mix up the input and output hoses of the filter and make sure that you don’t dip dirty water with the bottle that you’ll be drinking out of.
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Categories: Adventure

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