Boiling Water to Purify it

The need for safe and clean drinking water has been recognized for centuries already. History tells us that people in the olden times methodically collected rainwater and dug wells deep into the ground just to secure potable water. When none was found, boiling was the go-to solution to obtain drinkable water out of unclean water sources. Boiling water is effective in most situations and will remove bacteria and viruses to purification standards, but boiling will not remove many chemicals and other contaminants..

The popularity of boiling as a method of water treatment stems from two important factors: first, it kills all microorganisms present, and second, it is a very easy process that most households can immediately initiate should the need arise.

All that is required is a heat-resistant container to hold the water and a source of heat. What could be more simple? And yet with this simple process, most harmful bacteria, virus, protozoa, and parasites are eliminated almost immediately.

The process of boiling water

In fact, bringing water to its boiling point of 212° F (or 100° C) is more than sufficient to disinfect it from disease-causing contaminants. A study by the Wilderness Medical Society yielded an interesting discovery: most pathogens - or germs in colloquial terms - are already killed within 30 minutes when water is heated to above 160° F (or 70° C), and within a few minutes when the water temperature reaches 185° F (or 85° C).

With many pathogens are already done away with before water actually boils, you can be sure that when the boiling point is breached, microorganism count will be down to zero.

The length of time it takes for water to reach its boiling point depends on a few variable factors such as the amount of heat, the surface area of the container, and the amount and salinity of the water. At higher altitudes, water boils at a lower temperature so those purifying water above sea level should allow some extra boiling time just to be sure.

Even though the water is purified,boiling will leave the water with a flat taste so the boiled water should be aerated - i.e., poured from one container to another - to reduce the stale flavor.

Pathogens effectively removed by boiling

Water-borne diseases can be acquired from microorganisms commonly found in contaminated water sources including rivers and lakes. Listed below are the pathogens or microorganisms that boiling can capably remove:
  • Cryptosporidium - a type of protozoan (single-celled organism with animal-like behavior) found mostly in fecal matter that is known to cause gastrointestinal illnesses such as diarrhea and vomiting.
  • Giardia intestinalis or Giardia lamblia - another protozoan often present in human and animal waste that can also cause gastrointestinal diseases.
  • Bacteria such as Campylobacter, Salmonella, Shigella, E. Coli - may also cause gastrointestinal illness.
  • Viruses such as enterovirus, hepatitis A, norovirus, rotavirus - can cause gastrointestinal problems and other life-threatening diseases including meningitis and hepatitis.

The Pros: When boiling is the “best” method of purification

While boiling does eliminate a whole slew of waterborne disease-causing microbes, as a method of water purification it is only ideal for specific situations.

One such circumstance is when there is an emergency in a certain area; more specifically, a “water emergency.” This can happen when the water source is flooded, when there is an equipment or power failure in the water treatment system, or when there is damage to the pipeline. In such cases, local officials would advice residents to boil water (known as a boil order) to ensure the safety of their drinking water supply.

Boiling water for drinking is also the safest purification alternative when traveling. After all, experiencing diarrhea or stomach cramps is one sure way to ruin a trip. Boiling is practically the only option if you’re going camping or backpacking in the wilderness and have to source water from streams or lakes. But it can be a necessity as well when you are in a new place and are unsure about the cleanliness of the available drinking water in the area.

Lastly, for residents of underdeveloped countries that have no treated water systems in place just yet, water purification by means of boiling is the easiest, and for many, the only way of having access to potable water.

The Cons: Why boiling is not your go-to option

As the answer to regular supply of safe drinking water however, boiling simply won’t do.

For one, boiling is a tedious process relative to other more long term solutions. Bringing the water to a boil takes some minutes and getting it to cool down adds another few minutes. This is rather inconvenient compared to filtered water and treated water from the tap, where you simply pour and drink.

Secondly, it is not the most cost-effective option. Regardless of whether charcoal, wood, fuel, or electricity is utilized for heating, boiling expends a significant amount of energy. When this is done on a daily basis, the costs can add up. In fact, in countries without appropriate systems for safe drinking water, boiling water is a luxury that residents can ill afford. Most of them therefore, opt to take the risk of consuming potentially unsafe water than use up valuable energy resources.

But the most persuasive argument against boiling as a long-term water disinfection method is that it doesn’t remove any sediments found in the water and it doesn’t eliminate other types of water contaminants including chemical pollutants (e.g.lead, mercury, asbestos), toxic metals, and nitrates.

Exposed to these water contaminants for an extended period of time, people can develop potentially life-threatening diseases. Cancer, damage to the internal organs, bone-related diseases, allergies, and respiratory illnesses are only a few of the conditions brought about by these contaminants.

Boiling is highly advocated for emergency situations and for times when access to clean water is limited. But for long-term supply of safe drinking water, there are other far more appropriate technologies that can be adopted.

Additional Resources

Basic Water Boiling Information


Water Purification Systems and Filters

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