How to filter water ?

As a general rule, in so-called developed countries it is not necessary to filter tap water before drinking it. However, contrary to what many people think, drinkable water does not exist in its natural state. In the majority of cases, it must still undergo several treatments in order to comply with standards. This is why, in most European and North American countries, tap water is as safe and good, often even better than bottled water. 

For those who are more sceptical about water quality, however, there are more or less effective solutions for filtering it. In this article, I will talk about the best filtration methods to purify water when traveling, hiking, camping or even at home. This way, you will hopefully have no more excuses to keep buying plastic water bottles!

What type of water filter to choose ?

To improve the quality of water, whether it comes from the distribution network or from a rainwater harvester. From a well or a river, one solution: filtration.

There are several types of water filters, more or less efficient depending on the type of substances you wish to get rid of, namely :

Activated Charcoal

This is the most common type of filter, and is often used in combination with other filtration methods for maximum efficiency in removing toxins. The charcoal is treated to create a porous material that binds to certain toxins and impurities, allowing them to be removed from the water. This is called adsorption. A phenomenon that occurs when one material sticks to another as it passes through. This is the basic principle of activated charcoal. It is suitable for the removal of:

  • chlorine; 
  • chloroform;
  • agricultural chemicals;
  • organic substances;
  • sediment;
  • magnesium.

The activated charcoal filter also ensures that the filtered water has less odour and a better taste. Because it reduces the amount of chlorine and other contaminants that can make your water smelly or simply unpleasant to drink.

filter water bottle


Nano-filtration is used in water purification processes such as softening, decolorization, and removal of micro-pollutants. In industrial processes nano-filtration is mainly used to remove specific components such as colouring agents. Nano-filtration is a process that separates molecules based on their size and uses water pressure to operate. The process of separation is done through membranes. Contaminating elements contained in protozoa, bacteria and viruses are attracted and trapped in the filter membrane by nano aluminas. This technique is mainly used to remove organic substances, such as micro-pollutants.

Reverse Osmosis

The reverse osmosis filter has the ability to remove all kinds of contaminants that can be a danger to your health. It is a filtration technology that uses a semi-permeable membrane to separate inorganic contaminants from the water to produce drinkable water. Reverse osmosis is capable of removing most contaminants and a high percentage of toxins, such as:

  • fluoride; 
  • chromium;
  • arsenic;
  • nitrates/nitrites;
  • copper;
  • radium, etc.

However, with the exception of most soluble volatile organic compounds, some pesticides, solvents and chlorine.

Water ionizer

These filters use a process called electrolysis. This means that the water passes over electrically charged plates that change its molecular structure to produce:

  • Ionized alkaline water: rich in antioxidants (for consumption)
  • acidic ionised water: oxidising (for external uses such as cleaning and disinfection).

Although ion exchange is useful for treating water hardness and some radioactive materials, the filter does not remove organic matter, particles or bacteria as effectively as other filtration methods.

UV filter

When ultraviolet radiation is used to purify water, it has the ability to destroy various bacteria that can be harmful to your health. If you are looking for an environmentally friendly method to purify your water, a UV filter may be the best solution. Because it does not need chemicals or extra heat to be effective. However, it is important to note that UV filters only remove bacteria and viruses from the water. It is therefore important to use this filter in addition to other types of filters to remove the most common contaminants such as chlorine, lead and pesticides.

How to filter water when travelling ?

When travelling, especially when drinkable water is not easily available, the risks are mainly related to bacteria, viruses, protozoa and soluble particles in suspension. The filter bottle is the means I use because it allows me to drink water directly from the bottle without having to wait for hours unlike tablets and filter tabs. Today, these bottles are equipped with powerful antimicrobials made of fibre or activated charcoal. Most of them can effectively filter out about 99.9% of bacteria and protozoa and purify water from any source (except sea water and chemically polluted water), even stagnant water. For these reasons, the filter water bottle is also very useful for camping and hiking.

best tap water filters

How to purify water at home ?

When purifying tap water, the focus is on getting rid of bad taste due to chlorine or a particular odour. However, even though drinking tap water is safe for your health, filters can be helpful in getting rid of residues of nitrates, pesticides, drugs, lead, arsenic or aluminum, which may be present in small amounts.

As such, you can use reverse osmosis filters that are usually installed under the sink. Or you can use more affordable tap filters that are installed directly on your kitchen faucet. These filters also remove chemical residues, heavy metals, nitrates, pesticides and odours caused by chlorine.

The main advantage of filter jugs is in terms of taste for those who don't like the taste of tap water. This is because they hardly filter out any nitrates. Also, the fact that there is no more chlorine once the water has been filtered has the disadvantage of favouring certain bacteria since the water becomes more fragile.

Is the rainwater drinkable ?

Rainwater is not drinkable water. Due to its potential contamination as it passes through the atmosphere, runs off roofs, into a storage tank and then into the network, it is not immune to being loaded with metals, organic matter, organic micropollutants and micro-organisms.

Health regulations stipulate that drinkable water must not contain any microbiological pollutants. This is why rainwater should not be used for drinking, cooking, washing or laundry. The U.S. Federal Government does not have any laws or restrictions regarding rainwater harvesting. Most states allow citizens to collect rainwater, and even encourage them to do so.

filter rainwater

How to filter rainwater ?

To make rainwater drinkable from a sanitary and therefore legal point of view. First of all, it must be ensured that the ph of the tank where the water is stored is stable. Then, four efficient methods exist to make rainwater safe to drink:

  • microfiltration, with a pore size of about 0.01 micron;
  • ultra filtration, pore size about 0.01 micron;
  • nano-filtration, pore size about 0.001 micron;
  • reverse osmosis, pore size approximately 0.0001 micron.

These systems have their advantages and disadvantages, but they allow to obtain perfectly drinkable water.