Does Boiling Water Kill Bacteria?

Survival and disaster stories often have heroes boiling their drinking water before taking a sip. But does this method really work to eliminate potentially harmful bacteria and make water safe?

Fortunately, the answer is yes. Boiling water is one method of disinfection that helps protect public health — but it’s not the answer for all kinds of potential water problems. That’s because boiling only addresses certain kinds of contaminants such as bacteria, viruses and other disease-causing germs. It does not address issues such as toxic chemicals, heavy metals, radioactive materials and more.

Read on to learn more about boiling water — when and how to do it, what to expect and which solutions might be better in some cases.

How Boiling Water Works

Boiling can help eliminate certain contaminants like viruses, pathogenic bacteria, protozoa and more, because the heat from boiling can damage their structure and vital processes. As such, you don’t have to do anything special to boil tap water — you’re just letting science do its job.

However, it’s important to keep in mind that boiling isn’t the same as other water treatment processes. For example, because it only kills harmful organisms, it can’t be considered sterilization. Boiling is more similar to pasteurization — the process that treats many types of milk.

In many communities across the world, boiling is the primary (and sometimes only) method of water purification. That’s because a heat source is much easier to find or build than a full water filter system. Fortunately, public water systems in the U.S. and Canada are protected by rigorous treatment, testing and regulation, meaning it’s generally safe to drink your home’s tap water.

But there are some situations where a particular contaminant causes concern despite all of these preventive measures. In that case, public health authorities often issue a boil water advisory or boil order.

What is a Boil Water Notice?

Water line breaks, power outages, natural disasters and other issues can lead to unexpected failures in municipal water systems. These, in turn, can cause certain contaminants to reach your home’s water supply. Until it is determined whether water quality has been compromised and any problem has been addressed, local authorities issue recommendations or orders to boil tap water.

In some cases, an order is given to the water utility, which must comply. Generally, these guidelines are mandatory for restaurants, hospitals, hotels and other facilities regulated by health departments. The utility itself can also issue boil water advisories.

There’s a difference between “orders” and “advisories.” The former is a certainty and a requirement. The latter, on the other hand, generally comes into play when a contaminant may be in the water supply but hasn’t yet been confirmed. While consumers like you should always follow any type of boiling guidance, it’s regulated facilities — not people at home — who could face repercussions for failing to comply with a boil order.

Keep in mind that this guidance only applies to city water supplies. You won’t get an order or advisory if something goes wrong with your private well. Depending on the source and cause of the problem, it might sometimes be smart for well water users to follow the same guidance; however, complete well water safety requires a lot of different steps.

The Right Way To Boil Water

When you need to boil water at home, follow these steps. Start by inspecting it. If it’s cloudy, pour it over a clean cloth or paper towel, which will act as a simple filter. Then, take this filtered water and bring it to a rolling boil for at least one minute — or, at higher elevations, at least three minutes. Keep in mind that the boiling temperature of water is 212 °F (100 °C).

Next, let the water cool. Be sure to store it in a clean container that wasn’t washed with contaminated water. Don’t mix boiled and unboiled water, and don’t use unclean cups to draw the water, either.

This water should be saved for drinking, cooking, making baby formula and brushing your teeth. That’s because you can often keep using tap water for bathing, showering, laundry and hand washing, even under a boil advisory or order. If you have pets, let them drink the boiled water or keep bottled water on hand.

If you don’t like the taste of water after boiling, you can add a pinch of salt to each quart or liter of water. You could also pour the water from one clean container into another and repeat the process a few times.

What Boiling Water Doesn’t Do

Boiling can do a lot for water quality, but it doesn’t solve every possible problem. That’s when you need a more comprehensive solution like water filtration to get the job done.

Here are a few issues you can’t fix by boiling:

Heavy Metals

Some heavy metals can find their way into your water supply. Copper is perhaps the most noticeable contaminant with its metallic tastes and blue-green stains, but other metals could include lead, chromium and arsenic. Boiling won’t remove these contaminants.

Toxic Chemicals

Chemicals can end up in water systems, generally from human activity, and they can’t be boiled away. “Forever chemicals” are a particularly good example because, as the name suggests, they last a long time and are difficult to remove.

Mineral Content

Some mineral content in drinking water is good for you. Too much or the wrong type, however, can cause problems for you and your home. (Hint: If calcium and magnesium are among the culprits, you may need a water softener as well as a filtration solution.)

Taste, Odor and Color Issues

Many water quality issues are based on health risks. That’s generally not the case with taste, odor and color issues. While they can indicate other problems, these oddities themselves are often a concern just because they’ll make your water less palatable. That, in turn, could lead to trouble staying hydrated.

The problem is that boiling can’t address the vast majority of these issues, such as chlorine. While it may somewhat impact certain elements like taste or odor, it doesn’t address the underlying problems that lead to aesthetic concerns — for example, hydrogen sulfide causing a rotten egg smell.

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Water Filtration vs. Boiling

Boiling and water filtration can sometimes address similar contaminants, including certain viruses and bacteria. However, these are two different processes — and often, it’s best to let them work together in case of a boil order.

That’s because there are different types of filtration, each with its own methods and systems. Some, like reverse osmosis drinking water filtration systems, use multiple stages and kinds of purification to address a wide range of contaminant types. This can include everything from minerals and organic material to heavy metals and forever chemicals.

Health authorities don’t know what kind of water filter you might have, let alone how well it works. Just to be safe, they generally recommend boiling water during an order or advisory even if you use filtration.

But that doesn’t mean filtration is only a partial solution. Most comprehensive systems are a reliable solution for everyday water quality concerns, including safety as well as taste, odor and color issues. The problem only arises when something especially unusual happens — like a water pipe breakage or a natural disaster — that makes officials decide a boil advisory or order is necessary.

FAQs About Boiling Water

If you still have questions about boiling water, we have answers:

Does Hot Water Alone Kill Bacteria?

Hot water can reduce bacterial presence, but boiling is typically required to reliably kill most harmful microorganisms. However, according to the New York State Department of Health, heating water to 149°F/65°C for five minutes kills 99.99% of waterborne microorganisms.

For safety, always bring water to a full, rolling boil when following a boil advisory.

How Long Should I Boil Water to Kill Bacteria?

To kill bacteria and other microorganisms, bring water to a rolling boil for at least one full minute. If you’re at an elevation above 6,500 feet, boil for at least three minutes instead. These guidelines come from the U.S. Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO).

Is Boiling Enough to Purify Water?

Boiling can disinfect water by killing bacteria, viruses and parasites — but it does not purify water holistically. For example, it won’t remove chemical contaminants or heavy metals, and it can’t improve taste, odor or color. For everyday water quality concerns, a water filtration system is recommended.

Does Boiling Kill 100% of Bacteria?

Boiling at the proper temperature and duration is highly effective, often eliminating 99.99% of bacteria and viruses. However, because it doesn’t remove non-biological contaminants, it’s not considered a complete purification method. That’s why many people pair boiling (when needed) with home filtration systems for comprehensive protection.

Beyond Boiling: A Filtration Solution for Every Water Question

Boiling may be the answer to some water problems during an order or advisory, but what about day to day? That’s when it’s time to put filtration and softening to work. All you need to do to get started is have a professional water test, which will give you personalized insights into your home’s water quality.

Take the first step by scheduling your free, in-home water test and consultation today.