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Water Purification: Minimum Boiling Time and Other Methods

If you’ve got ever read about water purification on web forums or social media, it’s likely that you simply encountered not less than one one who asked, “how long should water be boiled before it’s considered secure?” This is a standard query, and one which’s prudent to ask — in spite of everything, you would not need to take any probabilities of consuming bacteria or protozoa that may make you severely sick. Unfortunately, this query has also led to the spread of some misinformation on the subject. (Sign up for our free newsletter to remain caught up on more life saving info like this!)

Water over rocks

Above: This water may appear clear and clean, but it will probably contain invisible pathogens that will certainly wreck your day.

Safe Water Is Crucial

The importance of utilizing secure, clean water can’t be overstated, in each on a regular basis and emergency scenarios. It’s the linchpin that holds the continuum of health, hygiene, and survival together. Unsafe water can harbor harmful microorganisms and chemicals that may cause serious health problems. Diseases comparable to cholera, dysentery, and typhoid can spread through contaminated water. By using secure water, you significantly reduce the chance of contracting or spreading these diseases.

Clean water is crucial for the body’s absorption of nutrients. It aids in digestion and ensures that the nutrients from the food we eat are effectively absorbed by the body. In emergency situations, gaining access to secure water could be a lifesaver. It reduces your vulnerability to diseases at times when medical resources could be scarce. Staying hydrated is significant for maintaining energy levels and physical health, especially during emergencies where physical exercise and stress levels could be high.

Safe water is crucial for hygiene practices like washing hands, cleansing, and cooking. It helps in stopping infections, maintaining a clean environment, and promoting overall sanitation. Utilizing secure water for cooking and cleansing food is crucial to forestall foodborne illnesses, which might be particularly hazardous in emergency scenarios.

Boiling Water

First of all, you might hear self-proclaimed “experts” on the web say that water should be boiled for a minimum time of 5 minutes, 10 minutes, and even 20 minutes to be certain that all waterborne pathogens have been killed. This minimum boiling time constraint is a myth, and we’ll explain why.

Scientific research tells us that waterborne pathogens (bacteria, protozoa, and viruses) are killed or inactivated at high temperatures. According to the Centers for Disease Control and Prevention,  a rolling boil for not less than 1 minute, will kill most bacteria, protozoa, and viruses.

Water purification warning sign

Most bacteria, protozoa and viruses might be killed in temperatures as little as 150°F, and we all know that water boils* at 212°F (100°C). This implies that by the point water has reached a rolling boil, it’ll be secure to drink.

Boiling Water at Higher Altitudes

*Now, there may be one essential clarification: the 212°F boiling point we mentioned is at sea level, and boiling temperature changes with altitude. The higher you’re above sea level, the lower the boiling point of water might be. For example, at 10,000 feet, the boiling point drops to 193.6°F (89.8°C). At the summit of Mt. Everest, an immense 29,029 feet, the boiling point is 158°F (70°C). So, even at the very best point on earth, bringing water to a rolling boil will kill pathogens in lower than 1 minute. For an added margin of safety, the CDC recommends boiling for 3 minutes at altitudes above 6,562 feet.


Above: While altitude changes the boiling point of water, it isn’t significant enough to affect purification by…

Filtering Water

You might think that by going to your local camping supply store, and buying a filter would solve the necessity for having to boil water. But you might be purchasing a misleading product in the event you aren’t aware of the nuances involved. To ensure you are getting the proper filter for the job, you must pay attention to what the filter rating actually means.

Water filters and purifiers are typically measured and rated to remove 99.X percent of viruses, bacteria, or protozoan cysts. Each digit on this percentage represents an influence of 10, also called a “log” (short for logarithm). For example, a filter rated to remove 99.99 percent of bacteria can be rated at a “4-log bacteria reduction.”

If your water had exactly 1,000,000 microbes in it, a 4-log reduction would mean only 100 of those microbes can be left within the water after treatment — 999,900 microbes can be removed. A 6-log or 99.9999-percent reduction would depart only one microbe within the water. 

If all of that was confusing, we cover it more extensively in our water filter buyers guide. But the long story short is: not all filters are created equally, and it pays to do your due diligence before counting on one for secure drinking water. Check out the video below to learn more about how water filters work, and what to search for on a label.

Disinfecting Water

Water disinfection is an important skill, especially in emergency situations where access to wash water could also be compromised. It’s a basic yet critical aspect of survival and preparedness. Here are several methods to purify water, making it secure for consumption:

  • Chemical disinfectants like iodine or chlorine tablets are portable and effective against many pathogens. They’re an excellent alternative for a bug-out bag or other portable emergency kit. The downside is they might leave an unpleasant taste, and they are not effective against some cysts like Cryptosporidium.

  • Portable UV light purifiers are also available. They’re effective against a big selection of microorganisms, including those immune to chlorine. The drawback is that they require batteries and will not work well in cloudy or turbid water.


  • Distillation involves boiling water after which collecting the vapor, which leaves behind contaminants. Distillation can remove bacteria, viruses, protozoa, and chemicals. It’s more energy-intensive and may not be essentially the most practical alternative in every scenario.


  • Q: How long does water need to boil to change into sterile?
    1 Minute in the event you’re below 6,562 ft (2,000m), 3 minutes in the event you’re above 6,562f
  • Q: Does boiling water for 10 minutes sterilize it?
    A:  Yes, but you mustn’t need to boil it for longer than 3 minutes.
  • Q: Will boiling water for half-hour achieve sterilization?
    A: Yes, but that is excessive unless you are attempting to distill water.
  • Q: What is the quickest method to sterilize water?
    A: In terms of speed, using properly rated filter might be going to be the fastest, followed by boiling, with chemical treatments and distillation being the slowest.
  • Q: How long should I boil water within the microwave to sterilize it?
    A: The same boiling rule (1 minute below 6,562ft, 3 minutes above) applies to the microwave, nonetheless, this might be potentially dangerous. Microwaves can heat water to boiling temperature without appearing to boil. Leaving the water within the microwave for too long can cause it to change into superheated and explode violently into steam. It is way safer, and more accurate to boil water by other means so you possibly can safely observe how long the water is boiling.
  • Q: Does boiling water kill bacteria?
    A: Yes. Boiling water will kill bacteria, protozoa, and viruses.
  • Q: Does boiling water make it secure to drink?
    A: Potentially yes. Although boiling water will kill biological agents, it’ll not remove chemical contaminants or radiation. Boiling doesn’t remove dissolved organic matter, the stuff that makes natural water sources like lakes and rivers appear amber or brown in color, and might make the taste seem different than cleaner water sources.

Final Thoughts

Anyway, don’t just take our word for it — hearken to the scientists. Here’s a direct quote from an article titled “Water Disinfection for International and Wilderness Travelers” from the Oxford Journal of Clinical Infectious Diseases:

Boiling water purification bacteria virus pathogen 2

So, here’s the underside line: Water doesn’t must be boiled for at least 5, 10, or 20 minutes with a purpose to be considered secure to drink. By the time it reaches a rolling boil, it will probably be considered secure, no matter your altitude. (Note: This assumes that no harmful chemicals or heavy metals, comparable to pesticides or lead, are present. To remove those contaminants, you will need a water filter/purifier.) However, you might proceed to boil for 1 to three additional minutes, or mix the methods discussed above for an additional margin of safety — in the event you’ve got a number of minutes to spare, it won’t hurt, but should not be considered mandatory.

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