How to treat water for drinking using established survival protocols

Iodine crystals for purifying water. Some people are highly allergic to iodine, so it’s a good idea to know that before you chose this as your preferred water purification technique.

When you’re desperate you’ll want to drink anything. But remember, most water isn’t safe in an emergency situation. Sure the stuff in your toilet cistern or water tank is probably OK if the system outside isn’t compromised but puddles, creeks, lakes and streams are usually contaminated with viruses, bacteria and protozoa. A good artisan spring is generally safe, as is fast moving snow melt. But really you can never be sure.

There are three main ways to treat water to kill microscopic organisms and we’ll examine each of them.

  • Man-made mechanical devices.
  • Chemicals
  • Boiling

Man-made mechanical devices

There are two types of mechanical hand-held devices: water filters and water purifiers.  Water is introduced into either device through a pumping action, is filtered and/or purified and discharged out as drinkable water.

A water filter will remove 99% of all bacterial contamination but it will not remove viruses.  In order to remove viruses, you would need to chemically treat the water or boil it.

Water purifiers contain a filter device, a charcoal medium that removes odors and tastes as well as a chemical that will kill viruses.

Filters last longer than purifiers.  A good filter will last for about 15,000 gallons of water before you have to replace the inside cartridge.  A water purifier will only treat about 100 gallons of water before the filter cartridge needs to be replaced.  All mechanical filters are fragile, and must be maintained, taken apart and cleaned.  They are expensive and, obviously, in order to be of use, you must have it with you.  This may not always be the case, particularly if your filter is at home and the emergency situation occurs while you are in the office.


Chemicals kill most of the viruses, bacteria and protozoa in contaminated water by essentially poisoning them.  This is the method that large municipal water treatment facilities use because it is the most cost effective method of treating large quantities of water.

There are several chemicals available to the individual that can be used for this purpose. These include: chlorine, bleach, chlorine bleach, and iodine.

Chlorine:  Liquid pool chlorine is extremely caustic and must be handled with care. Prior to drinking and in order to make it taste better, water treated with chlorine can be exposed to the air and the chlorine evaporates out.

Bleach/chlorine bleach:  These are also caustic chemicals that must be handled with care.  These are regular household bleaches sold in the supermarket.  Again, to make it taste better, before drinking, you can expose the water to the air and let the bleach dissipate.

How much bleach should you use? The rule of thumb for treating a gallon of water is 12 drops and wait thirty minutes.  This should kill off the majority of the harmful critters and it is an easy rule to remember.

Iodine:  It is a periodic element.  It doesn’t breakdown into any smaller units.  It comes in three forms:  as tablets, liquid or as iodine crystals.

Iodine tablets:  Convenient but expensive to use.  A bottle of tablets may contain 50 tablets.  It takes 3 tablets per quart and they retail for $6-8 per bottle.  Once opened and not used, they will have a shelf life of several months at which point the iodine has evaporated.  We don’t recommend tablets unless they are the only thing available.

Liquid iodine:  Is usually sold as a liquid solution.  Brand names include Provine and Betadine, which are used in the medical and veterinary professions.  The least expensive way to purchase it without a prescription is to go to the feed and tack store and buy it in quarts or pints.  Use 12 drops per gallon and wait 30 minutes.

Iodine crystals:  Small metallic looking beads that when immersed in water, saturate the water to a solution of iodine.  The strength of the solution is contingent upon the amount of water and the amount of crystals present.  It is variable.  Iodine crystals have the advantage of being easily transportable and because they can be diluted with water and then left to evaporate they become an almost perpetual iodine making machine.

A small bottle will generally treat about 500 gallons of water before the crystals are used up.  This is a very economical method and the one we recommend.  For the amount to use, follow the directions on the bottle

Notes:  Chemicals are caustic and particularly dangerous if mishandled.  Use your sense. Don’t leave any chemicals where there is a risk of cross-contamination. Keep away from children, food preparation areas, cooking utensils and pets. 

Some people have a serious allergic reaction to Iodine.  Check for this BEFORE an emergency situation arises.


After speaking to representatives from EPA, CDC and local municipalities, we decided to keep it simple.  The best method of treating water is to boil it.

But for how long?  Research provided interesting and varying answers which ranged from just bringing it to a boil, to boiling for 1 minute; to 3-5 minutes; to 10 minutes; to 15 minutes; to 20 minutes.  The differing time ranges are based on the contamination level, the source of the water, and the elevation.  We did some follow-up research with biologists from Environmental Health offices and determined that the safest method would be to bring the water to a rolling boil and continue boiling from 10-15 minutes depending on your own personal level of paranoia.  But, definitely no less than 10 minutes.  To minimize the amount lost to evaporation keep the pot covered during the boiling process.

Ten minutes will kill the majority of micro-organisms. Note well, however, that it may take up to 20 minutes to kill the most resistant of spore-stage viruses. Fortunately, viruses constitute a small percentage of water-borne pollutants but if you have immune-compromised people dependent on this water, such as very young, very old, or very weak people you probably should opt for greater caution.

If you have a limited supply of water there are several things to be aware of:

  • Don’t eat because it takes water to digest food.
  • Don’t smoke because it dehydrates your lung lining.
  • Don’t drink alcohol of any kind because your body has to digest it and the body needs water for the digestion process.  The same is true for soda, coffee, tea or any other caffeine drinks.
  • If you must travel do so only in the cool hours of the evening and the morning.
  • Wear light-colored clothing, avoiding sun on your skin.
  • Move slowly so you don’t lose moisture through perspiration or respiration.
  • Don’t do any physical labor.
  • Stay out of the sun and the wind.
  • While the Army Manual says don’t drink your urine, there are arguments for it in a dire emergency. A healthy person’s urine is about 95 percent water and sterile, so in the short term it’s safe to drink and does replenish lost water. But the other 5% of urine comprises a diverse collection of waste products, including nitrogen, potassium, and calcium—and too much of these can cause problems. When you drink your own pee, all the stuff that your kidneys had attempted to excrete comes right back into your stomach, and much of it ends up back in your kidneys. After several days of this, your urine will become highly concentrated with dangerous waste products, and you’ll start on the road to total kidney failure.