Water filter versus water purifiers, what's the difference?
Water Filter vs. Water Purifier: What’s the Difference?

Is water filtration and water purification the same thing? If you’re new to the world of water filtration and purification, a question like this may leave you with even more questions than answers.

Once you’ve completed reading this article, we hope that you’ll be able to confidently shop for your ideal water filter or water purifier and reap the benefits of pure, clean water. Let’s dive in!

But first…

Why does one need to filter or purify water? Municipalities add water treatment chemicals like chlorine to your tap water. The pipes used to get the water to your house may also be old and rusty and have leakages that introduce rust, sediments and harmful contaminants. Best avoided!

For the more curious minds, please read on for more detail …

What Is a Water Filter?

A water filter filters water through a membrane or a filter medium like ceramic, carbon or sand. The effectiveness depends on how small the pores are in the membrane or the spaces between the elements of the filter medium.

For example,

  1. Ultrafiltration has a pore size of around 0.01 micron and removes all contaminants, including some viruses.
  2. Reverse Osmosis, has a pore size of around 0.0001 micron and removes protozoa, bacteria, viruses, and common chemical contaminants.
  3. Ceramic filter medium, has a pore size of around 0.5 micron. We use this in our Stefani Water Filters.

GAC (Granular Activated Carbon), has a pore size of around 20 micron. We use this in many of our countertop water filters  and undercounter water filters.

Types of Water Filters & How They Work

These are the main types of water filters you can install in your home and/or office.

Whole-house water filter

A whole-house water filter system services, well … your whole house, and it’s able to do this because it’s connected via your incoming water mains.

In many whole-house water filter systems, such as our Double Big Blue 20-Inch Water Filter and Triple Big Blue 20″ Water Filter, the water passes through several processes – initially through a sediment pre-filter, which captures sediment, silt and rust particles, and then through a granular activated carbon filter, which removes chemicals like chlorine and harmful organic contaminants. It also improves the colour, taste, and odour of your water.

In the case of the H2O | BWT AquaStar UV, it does all of the above and disinfects the water with a UV unit.

Diagram showing the features and benefits of the Aquastar UV water filter

Oftentimes, you may have several water challenges that you need solved. In cases like that, we will design a treatment sequence for you; a line of water treatment units, each performing their own function, to give you amazing, clear, safe and pure drinking water no matter the source or contaminants.

Countertop water filter

An image showing a variety of H2O BWT countertop water filters

Being able to simply attach countertop water filters directly to your faucet (as would be the case with our Deluxe Countertop Purifier Chlora+), can be wonderfully convenient if all you require is pure, filtered drinking water.

Undercounter water filter

Undercounter water filters are just as convenient to have in the kitchen as countertop water filters, what’s more, they also open up much-needed countertop space.

Shower water filter

Harmful chemicals and particles can also affect your skin and hair, leaving them feeling dry and uncomfortable. If this is an issue you think you may have, investing in a water filter shower head might be a good idea. All you have to do is attach it to your shower spigot and you’re ready to go!

What Is a Water Purifier?

Water Purifiers

You wouldn’t be completely incorrect by assuming that water filters and water purifiers are the same things. They indeed function very similarly, both water purifiers and water filters work by removing impurities in your water.

The difference is that a water purifier goes a little deeper by eliminating biological contaminants and removing certain minerals, leaving only the purest drinkable water behind. Water purifiers can use either Reverse Osmosis, Chemical Exchange, Distillation, UV Treatment, or a combination of these methods.

Here’s a quick breakdown of how each of these methods of purification works and why they may be necessary.

Reverse Osmosis

H2O BWT reverse osmosis products

Reverse osmosis, which pumps water through a porous membrane, might be categorized as water filtration, however, because it demineralizes or deionizes water through a semi-permeable reverse osmosis membrane, it is considered to be a form of water purification. As a result, it is not straightforward water filtration.

Please note: Purifiers using reverse osmosis (RO) may end up removing all minerals, including the good ones! We recommend that you invest in a RO water purifier with a remineraliser which adds the good minerals back into the water. Take a look at the specifications of our RO water purifiers to find out more about how this process works.


This term may sound familiar, and it is simply the boiling of water, which creates steam, which is by its very nature utterly pure ﹘no contaminants remain in the steam. The steam is then condensed back into pure water. H2O | BWT does not use distillation on their wide variety of water filtration and purification products. This is a process usually only used in clinical laboratories.

What are the risks of drinking distilled water?

The main dangers of drinking only distilled water are related to its deficiency in minerals like calcium and magnesium. According to an older report for the World Health Organization (WHO), the following are some negative impacts of consuming only distilled or low mineral water:

  • A flat flavour that may be unpleasant, causing you to drink less water
  • A decline in metabolic activity within the body
  • A rise in urine production that can cause electrolyte imbalance

The WHO claims that the absence of minerals and electrolytes in distilled water is a contributing factor in these and other related health issues. This deficiency may cause potentially unhealthy changes to the body’s sensitive sodium, potassium, fluid, calcium, magnesium, zinc, and phosphorus balance.

In addition to water, the body also loses sodium and other minerals as it excretes urine and sweat. A person needs to replenish certain minerals for their body to function properly.

Since all additives and minerals will have been eliminated during the distillation process, drinking distilled water won’t restore minerals lost through perspiration.

Any material that distillate water comes in contact with, including plastics and the human body (even the teeth), absorbs trace amounts of minerals. However, a person shouldn’t become deficient if they consume a balanced diet that includes the required amounts of fruits and vegetables.

Most people will obtain the salts and minerals they require from these other sources because they consume a range of foods and beverages throughout the day.

Consuming distilled water as part of a healthy diet is not harmful. Foods that replenish any minerals lost via sweat should be a part of a balanced diet.

UV Treatment

H2O BWT AquaStar UV Water Purifier

Ultraviolet water purification is one of the most effective ways to eliminate organisms from water. In this process, ultraviolet light penetrates the water, eliminating organisms, such as viruses and bacteria. Have a look at our AquaStar UV Water Filter to find out more detail about how this process works.

Contaminant Exchange

Diagram showing KDF process

A good example of a chemical exchange is our exclusive KDF water purification medium, it exchanges harmful contaminant electrons (found in chlorine, iron, hydrogen sulphide, lead, mercury, calcium carbonate, magnesium, chromium, bacteria, algae, and fungi) into harmless components.

In conclusion:

In the case of filtered water vs purified water, the best way to conclude this is the following:

  • A water filter is used to remove basic contaminants like sediments, rust and chemicals. Typically, good minerals remain and the taste of water is improved.
  • However, Ultrafiltration is an advanced water filter, the pores are so fine that they remove all harmful contaminants up to 0.0001 microns.
  • A water purifier is more scientific in that it uses chemical processes like ion exchange, UV or very fine membrane pores to give you pure water, depending on your need.

Sometimes, water filtration and purification are performed in one water treatment unit. Watch the video to see the working of one of our water filters that do this, or the working of a full Reverse Osmosis System with filters and remineralisers.

Hopefully, after diving into this well of information on water purifiers vs water filters, you’ll find it easier to make the right choice, whether you choose a water filter or purifier is up to you and largely depends on the quality of water you have access to, and the filtration or purification result you need.

H2O BWT offers a vast variety of high-quality water filters and water purifiers, so you can be certain you’ll find the right fit for your home or office.

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