Boiling Water for Drinking: What Temperature and How Long?

Boiling Water for Drinking Title Image

In a best-case scenario, your water source is never jeopardized, even after natural disasters. Of course, this is rarely the case.

If your water is contaminated or flow is restricted, the next-best scenario would be for you to have plenty of water already on hand in your stockpile.  Not everyone is well-equipped for natural disasters though, and even those who are, eventually run out of clean water. It’s crucial to know how to purify your water using a variety of methods.

Today, I’ll be showing you the preferred method of boiling water for drinking.

Boiling Water for Drinking

Boiling water is the most common water purification method available during emergencies. During a disaster situation, local or regional water sources  may become contaminated. That is why you’ll often see government agencies recommending that citizens in a certain area boil their water prior to using it. However, this method is equally effective when backpacking or just trying to survive in the wilderness.

This method involves heating water to a temperature at which bubbles begin to rise from the water. This temperature makes it uninhabitable for microorganisms such as bacteria, viruses, and parasites. It’s the surest way to kill microorganisms and make it safe to drink. Here is a guide for boiling water.

A Step-By-Step Guide to Boiling Water

1. Filter Your Water

  1. If the water has visible particles, then filter it as best as you can by passing it through a piece of clothing or scrap cloth. This step may not be necessary if you can’t see any particles in the water and the water is clear.

2. Find a Source of Heat

  1. This can vary depending on your location and the emergency. When camping, light a campfire. When indoors, light up your stove top. If you have a gas stove, you don’t need electricity to light it.
  2. However, regardless of the source chosen, ensure that you don’t put yourself in more danger. For example, if your home or area becomes flooded, avoid the risk of electric shock by keeping your electronic powered devices off/unplugged (this includes your stove top), even if the power is still on. Better yet, flip your breaker box off entirely. 

3. Use a Container and Heat Your Water to Boiling

  1. Find a container, preferably metallic, pour the water inside and place it on the heat source. The duration of this will vary depending on the altitude of your location.
  2. Those in higher altitudes will see their water boil faster. This is because the boiling point of water is at a lower temperature at high altitudes.

Altitudes of less that 6,500 FeetBoil for 1 minutes.

Altitudes at or over 6,500 Feet: Boil for 3 minute.

4. Let the Boiled Water Cool

  1. After the water has boiled for about one to three minutes depending on your altitude, let it cool. Allowing it to cool lowers the temperature of the boiling water and helps it have an improved taste again.
  2. Once cooled, you can then drink the water, or store it in clean sanitized containers with tight covers.
  3. Because water takes about a half hour to cool, it’s wise to boil more water than you need. This will prevent you from having to choose between being thirsty and having to drink hot water.
Boiling pot of water on the stove.
An optimist believes he has enough clean drinking water. A prepper carries along a matchbox and a pot to purify water in, just in case he doesn’t.

Why Boiling Purifies Water

Boiling purifies water through heat. The heat supplied by the source raises the temperature of the water to about 212°F (100°C). This temperature is too high to support life.

Advantages of Boiling Water for Drinking

  • Boiling is the most straightforward means of water purification available during emergencies or natural disasters. Emergencies often mean that you won’t have access to essential services or supplies, such as clean water.
  • When you want to purify water, you have to use the resources available. Boiling only requires a heat source and something to boil the water in. 
  • Boiling purifies your drinking water. Some emergencies such as flooding can often compromise the integrity of drinking water. However, boiling kills the disease-causing microorganisms that are often in your drinking water.

Disadvantages of Boiling Water

  • Ongoing studies have shown that boiling kills only about 99% of the microorganisms.
  • These studies reveal that the microorganisms can form a cyst around them when temperatures rise beyond what they can stand. This adaptation helps them survive even temperatures as high as that of boiling water.
  • Boiled water can be re-contaminated. This usually occurs when the water isn’t stored correctly in sanitized containers. 
  • Though it kills bacteria and living organisms, boiling water doesn’t remove turbidity, taste, smell, color or chemicals.
  • Boiling water does not remove arsenic and other chemical pollutants. To remove or reduce chemical contaminants, consider using a carbon-based filtration system.
  • Boiling water that has a lot of calcium, iron or chlorine is not ideal, because minerals don’t evaporate. This will leave you with concentrated mineral water, which can lead to kidney stones or other health issues with continued consumption

Alternative Ways to Purify Your Water Using Heat

When heat sources aren’t available, you’ll have to improvise. In such circumstances, try using other means such as heating drinking water the natural way, using the sun.

Using the SODIS Method

Solar water disinfection or “SODIS” enables you to leverage on ultraviolet (U.V.) rays to purify water. See this guide on how to purify water using the SODIS method. 

Heating this way allows you take advantage of the natural energy provided by the sun. This method can be better than boiling since fire is not required. All you need is the sun and a clear plastic bottle. Heating using the sun helps you take advantage of the natural source of heat and U.V. rays to sterilize the water.

Using a Solar Cooker

A solar cooker can be used to bring the water up to a temperature that adequately purifies water. It is recommended to leave the water on the cooker for about five minutes at 140°F (60°C) or above with a solar cooker.

Purifying Water at Lower Temperatures

In some situations, you may find yourself being able only to heat the water and not have access to an open flame to boil it. Such conditions can be very tricky as you may not know whether the water is safe for drinking or not since you can’t just watch for a boil to occur as a sign that it is safe.

Research shows that waterborne pathogens are often inactivated or killed at high temperatures. WHO (the World Health Organization) recommends that heating the water to a temperature of at least 158°F (70°C) for a minute will kill 99.9% of the pathogens.

“If you can’t reach the boiling point, heating water at 140°F (60°C) or higher for about five minutes should kill any pathogens that are present.”

– Charles Hamilton (

Pouring water after boiling it, while camping.
Drink your water immediately after it has cooled, or store it in a sanitized, airtight container. Don’t let the water become contaminated again, it’s unsafe to repeatedly boil drinking water.


Failing to purify the water can be dangerous. This is because it could result in waterborne diseases that can cause vomiting, diarrhea, or even death without proper treatment.

A World Health Organization report indicates that as of the year 2014, there have been over 842000 deaths that result from waterborne diseases annually in the world. Simple water purification methods could have prevented these deaths. There are so many ways to clean and purify water. Using heat to disinfect and clean water is one of the most straightforward methods of ensuring the water you drink is safe.

Have you ever been told by local authorities to boil your tap water before consuming it? Tell us about it in the comment section below!

John Walter

John Walter is an emergency preparedness consultant with eight years of experience and training in related fields. He is a passionate prepper living in the Sacramento area of California.

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