Posted by Devin Peterson on 2/7/2012 to Water and Hydration

Disinfecting and purifying your drinking water in a survival situation is extremely important. Below we have outlined a variety of techniques you can apply when you have come across non potable water and must hydrate yourself with no other options. It does not matter whether your source of water is a river, a pond, a puddle, morning dew, rain, ice, snow or whatever the case may be, you may run a great risk by not purifying and sanitizing the water before you drink.

The difference between purification, filtration, and disinfection.

Disinfecting your water means to kill or inactivate harmful pathogens that are biological in nature, such as viruses, bacteria, and protozoa. Filtration means to remove particles and pollutants. Purifying your water includes disinfection, but also means to filter out other particulates not safe for human consumption such as chemical constituents and large particulates from debris.

It is important to distinguish that purifying your water is better and more comprehensive than just disinfecting or filtering your water.


1.Using a Water Filter

Water filters come in various types and sizes and are probably the easiest method of purifying your water. In general, they are effective in removing all large debris and microorganisms larger than  .02-.03 of a micrometer. However most viruses and some bacteria and protozoa can still get past the standard water filter. It is often required to take an additional step in disinfecting your water before you pass the water through the filter. Another con about using a water filter is that over time they can easily lose their effectiveness and even become a breeding ground for pathogens. To conclude, water filters are simple and cheap and are mostly effective when combined with another form of disinfection. If you do not have a designed water filter there are makeshift ways to filter out large particles such as by passing the water through a cloth or article of clothing such as your sock, glove, hat, or shirt.

2. Chemical Disinfection

Disinfecting your water chemically can be done using a variety of chemicals that all work great for killing microorganisms. Below are some of the more popular and proven methods of chemical water disinfection.

Iodine – Iodine can be used as a liquid solution, tablets or as iodine crystals. Generally, iodine water disinfection is incomplete as it does not kill ALL pathogens, but it does kill the most common ones, making it a great and cheap solution for disinfecting your water for emergency situations. Iodine is known to leave a terrible taste after using, so many water purification kits come with an additional additive of vitamin C (aka ascorbic acid) to improve the taste of the water.Chlorine – Halazone tablets with a chlorine base are the most common chlorine water disinfectant products for drinking purposes. These tablets are generally more effective than iodine but retain a shorter shelf life after exposure. Chlorine bleach can be used to disinfect water for drinking when proper dosage is followed and allowed to stand for 30-60 minutes. 2 drops of 5% unscented bleach in 1 liter of clear water can be safe to drink after being covered for 60 minutes and then opened for a few extra minutes. 3. Boiling

Boiling your water is one of the most sure fire ways to disinfect your water. Although there is some debate over how long water should boil it really depends on what possible contaminants are at play. Most pathogens will be killed before boiling point is even reached in normal atmospheric conditions. But sometimes extended boiling is required, especially in higher altitudes where water boils at less than 100 degrees Celsius over an open fire. Boiling your water may not remove pollutants that have boiling points above 100 degrees Celsius. However, using a charcoal filter system in conjunction with boiling your water is a great way to purify your water when both pathogens and pollutants are present. Learn how to build a fire here.

4. Solar and Ultraviolet Purification

Ultraviolet light will kill most pathogens in a relatively short amount of time. There are special devices that harvest the power of ultraviolet light for water disinfection purposes. SteriPEN is the most popular brand. Without a SteriPEN device, you can still use the power of the sun to disinfect your water using ultraviolet light. However, this method takes longer and is less fool proof. To disinfect your water using the sun you will need a very clear, transparent and sealed bottle. Fill the bottle with water and shake to allow air bubbles and simply let sit in direct sunlight with a heated back drop of some kind, like a metal roof or black surface that can be heated up by the sun. It is the combination of UV light and heat that kills the pathogens. If the direct light is strong and water is heated then 6 hours is generally enough time to disinfect the water. But sometimes it may take up to 2 days depending on weather conditions.


Water Purification Conclusion:


It is best to combine 2 different methods, one that filters and one that disinfects. There are many techniques to making home filters or makeshift water filter systems and boiling is always a reliable water disinfecting method.


Want to know how to find water in the wilderness?


Recommended Water Survival Gear by Cliff:


Aquamira 2 Part Water Treatment, SteriPEN Fits All Filter, Water Flask, Aqua Blox


Recommended Water Survival Gear by Skip:


Coghlans Germicidal Tablets, SteriPEN handcranked filter, Water bladder, Aqua Literz


  1. Bulldog13 says:

    I am using 55 gallon, food grade plastic, sealed top barrels with two, 2 inch bung holes to store water. Before drinking, I will purify with a Berkey filter. The barrels originally were filled with distilled white vinegar. Needless to say, a 55 gallon barrel with only two small holes in the top is going to be hard to sanitize. I have been told to use something called Star San. One ounce per 5 gallons, so eleven ounces per 55 gallons. Has anyone used this on food grade plastic sealed barrels? How is the best way to use it? Soak, let sit, rinse etc? I have no idea the best way to sanitize the barrels. Any suggestions? Thanks, Mike.

    • John Milandred says:

      I have never used Star San! but if the barrels had distilled vinegar in them they are already sanitized.Just rinse them out 3 times and on the forth time let the water sit in them for a day, then rinse 1 more time….Your lucky!