Ahh, the million-dollar question! And how do you know if your water is safe to drink? While most city water supplies are regulated for quality and safety, it’s always worth being aware of any potential hazards. In developed countries, we always tend to rely on the local health and safety regulations, but these are only good if people follow them by the book. And as we are only human, mistakes do happen.

Boiling your water is one of the oldest known methods for purification and can help ensure that potentially hazardous waterborne pathogens or contaminants are eliminated from the drinking supply. In fact, I still remember my grandma boiling our well water in the rural area, when I was little! However, the one big caveat here is that it can only ever protect you against organic contaminants, such as bacteria and certain viruses. Boiling your tap water makes absolutely no difference to any metal, non-metals, or other chemical contaminants.

Let’s discuss why boiling water might be necessary, how long you need to boil your water to ensure it has been properly purified, as well as some other tips on keeping clean and safe drinking water in your home.

What Bacteria Does Boiling Tap Water Remove?

Boiling water kills bacteria by a process called ‘lysis’. In other words, the close to 100C water causes the cell walls of bacteria to break down, allowing the cells to pop. Lysis is lethal to most bacteria, including those that cause food poisoning and disease. Boiling water is an effective way to kill bacteria and other pathogens, making it safe to drink.

Boiling water can kill a lot of the commonly found types of bacteria and viruses. For example, boiling water can kill:

  • Escherichia coli¬† aka E. Coli
  • Salmonella
  • Shigella
  • Vibrio cholerae (cholera)

Boiling water can also inactivate viruses, such as:

  • Influenza
  • Adenovirus
  • Norovirus
  • Rotavirus

Heat resistant bacteria

It is however important to remember that there are also going to be bacteria and viruses resistant to the high temperatures of boiling water. For example, thermophilic bacteria and fungi are those that can withstand huge variations in temperatures in pH. One such example is the organisms that exist in hot springs!

Hot springs with bacteria

Thermophilic bacteria absolutely thrive in extreme ranges of temperature, such as in this hot spring.

Heat resistant viruses

Other viruses, such as the hepatitis A virus can withstand briefly high temperatures of up to 100C. For this reason, it is not enough to simply bring the water to boil, if you want to be certain that you are getting rid of as many organics as possible.

Generally, we would recommend boiling water for at least one minute to kill most bacteria and viruses.

The reason some viruses are able to withstand such high temperatures is that they are protected by a protective outer layer. It can therefore take some time for this outer envelope to break down, in order to fully inactivate the virus.

Did you know?

At higher altitudes above 2,000 meters, water should be boiled for at least three minutes. This is because the boiling point of water decreases at higher altitudes, so it may take longer to kill the same bacteria and viruses.

Once you’ve boiled the water, remember to let it cool down before drinking to avoid scalding your mouth.

What else does boiling tap water remove?

Other than bacteria and viruses, other boiling water also removes protozoa, which may also be responsible for causing certain infections. In fact, a protozoan called Giardia is the most common cause of waterborne disease outbreaks in North America and Europe.

Does boiling tap water remove chemicals?

Boiling tap water does not remove chemicals. Some of the most common (and harmful) types of chemicals such as Arsenic, Lead, Nitrates, Pesticides, PFAS (Perfluoroalkyl and Polyfluoroalkyl Substances), and other VOCs (Volatile Organic Compounds) are unfortunately not removed by boiling tap water.

arsenic lead and nitrate fertiliser

The only way to remove these is through special filtration techniques. Of course, the only way to actually check whether your tap water has any of these, and their concentration, is to get your tap water tested.

So should I boil or filter my tap water?

This really depends on what you are trying to achieve. If you are worried about both organic and inorganic contaminants, then the answer is both. Boil the water first, then filter it once it has cooled down.

The reason you should boil first and filter second is that the process of boiling bacteria can cause a rise in the levels of nitrates in the water. As the bacterial envelope opens, this may release nitrate, potentially to dangerously high levels. However, using the right filtration technique afterwards, could potentially eliminate the excess level of nitrate.

Are you still concerned about contaminants in your tap water? If so, get in touch with us or browse through our wide selection of tap water tests. All our lab tests are provided by UKAS-certified independent labs contracted directly by Aqua Vue Ltd. The labs provide their official report, which we interpret and then forward directly to you, in as little as 5 working days. Send us a message at [email protected] if you have any questions – we’re a friendly bunch!