Water Purification

There are several elements that share commonalities among all methods of water purification.  These include water temperature, sediment level and contact time.  The least amount of sediment you start with, the better.  Prior to purifying, it is a good idea to run the water through a bandana filter several times to start filtering out the sediment.

One point of note.  It is important to segregate the containers you use to purify water, if at all possible.  Use a different container for impure water from the container you store your purified water in.  If possible, never mix functions of the two containers.

If you are lucky enough to have a clean container and a clean way to catch it, rainwater is usually safe to drink.  However, if you are catching it off of a roof, you still need to purify it.


BOILING


The easiest way to purify water.  It kills everything, but will not neutralize chemical pollutants that might be in the water.  Of all purification methods, it is the most certain way to kill all organisms, if it is done correctly.

To purify, the water temperature must exceed 160 degrees F to kill all pathogens within 30 minutes.  Greater than 185 degrees F will kill all pathogens within a few minutes.  Since the boiling point of water is 212 degrees F, boiling for a few minutes will kill all pathogens, even at high altitudes.

The downside to boiling is that it removes oxygen and the water ends up tasting flat.

To purify using boiling, you obviously have to have a heat source (i.e. fire), and containers.  If you have a fire-proof container, you can simply boil it in or over the fire.  If you do not, you can boil indirectly by rock boiling.

To rock boil, place stones in the fire, wait for them to heat up, then remove and place into the container full of water.  You will need enough rocks in the fire to keep adding to the container often enough that the water comes to a boil and stays boiling for the required time.  This method obviously takes a degree of skill and finesse.

Studies vary on boiling time.  Some state that as fast as one minute, others much higher.  A good rule of thumb is to boil for at least 5 minutes.  Be sure to let it cool down before drinking!


CHEMICAL


Two main methods:  Iodine and Chlorine.  Neither kill all pathogens, so there is a degree of risk.

1.  Iodine:  NOTE:  use of iodine by itself as a purification system will NOT be effective against Cryptosporidium.

Iodine is light sensitive and must always be stored in a dark bottle.  It works best with water temperatures over 68 degrees F.  Studies show that it is more effective than Chlorine in inactivating Giardia cysts.  Iodine does lose it's effectiveness over time, so be sure to check the expiration date on any iodine type used.

NOTE:  Many individuals have iodine allergies and cannot use it.  If the individual is allergic to shellfish, they will be allergic to iodine and cannot use this method.

a.  Liquid 2% Tincture of Iodine:  add 5 drops to a quart of water when the water is clear, 10 drops to a quart of water when the water is cloudy.  Let sit for at least 20 minutes.

b.  Potable Aqua (Iodine Tablets):  There are a variety of these out there, so be sure to closely follow the manufacturer's recommendations.

2.  Chlorine:  Chlorine will have low to medium effectiveness to Cryptosporidium, and is the go-to chemical purification method when individuals are allergic or cannot use Iodine.  Use 8 drops per gallon of water if the water is relatively clear, up to 16 drops if the water is cloudy.  Mix well and let sit for at least 30 minutes.  Pre-filtering helps alot.  The treated water should have a slight bleach smell.  If it does not, re-treat the water.


FILTRATION


NOTE:  Filtration of water in the bush without the aid of specifically designed very small micron filters, will not purify water.  Since little will be available in the bush to effectively filter down to a small enough micron size, many viruses will not be effectively filtered, although a good field charcoal filter will probably filter out all most protozoa and many bacteria.

To use the filtration method, it is important to use the cleanest water you can find.  Pre-filter the water as much as possible before filtering.  If you must filter dirty water, allow it to settle as much as possible prior to filtering.

To build a filter in the bush:

     1. Cut a 14x14 piece of birch bark in one single section.
     2. Roll the bark into a cone (like you would a newspaper), leaving a penny size hole at the bottom.
     3. Tie with cordage.
     4. Place several small stones at the bottom.
     5. Place alternating layers of grass, sand and crushed charcoal (get your charcoal from your extinguished fires.  If you already have a fire going, boil!).
     6.  May have to filter multiple times.


.....Research is fun and all, but I'm ready to get out in the woods and do something!!