Water purifiers essentially do all what water filters do, and in addition remove all minerals from water. Sounds confusing? It shouldn’t! Let’s break it down step by step.

Water filters are used to trap contaminants in water. This can be done through a number of technologies, of which the most popular are:

  • Activated Carbon filtration
  • Ultrafiltration
  • Sediment filtration

The four above-mentioned methods have different degrees of effectiveness regarding the range of contaminants they can get rid of.

Activated Carbon Filters

These are made from granular pieces of carbon tailored to be more porous. Activated charcoal filters can remove the following contaminants from water:

  • Chlorine and chlorine by-products
  • Chloride
  • Pesticides
  • Herbicides
  • Nitrates
  • Phosphates
  • Lithium
  • Pharmaceuticals
  • Microplastics

UF Water Filters

These use hollow fibers of membrane material(usually with 0.02 micron diameter) to trap water contaminants. UF filters can get rid of the following:

  • Colloids
  • Proteins
  • Bacteria
  • Viruses
  • Endotoxins
  • Silica
  • Smog
  • Silt
  • Plastics

Sediment Filters

These basically remove suspended solids from water through mechanical filtration. These include:

  • Dirt
  • Debris
  • Flakes of rust
  • Turbidity

You will agree that the above-mentioned contaminants do not represent the entire range of contaminants usually found in water. Water purifiers come in handy to get rid of the other water pollutants.

How does water purification work?

Water purification can be done through two main processes:

i) Reverse Osmosis

ii) Distillation

Distillation is not that common in households as it involves boiling water and condensing the steam. Reverse Osmosis is the popular option here. It basically makes use of a semi-permeable membrane with very small mesh size.

We just mentioned the average mesh size of UF filters as 0.02 micron. For RO filters, the semipermeable membrane is rated as tiny as 0.0005 micron. Quite a difference! And that’s what makes reverse osmosis that effective.

Water is forced to pass through the membrane by application of pressure. Water molecules are averagely sized at 0.000282 microns. These can successively pass through the filter membrane while blocking lots of other contaminants. In fact, any contaminant with a molecule size larger than 0.0005 micron will not pass through the membrane.

Consider the following:

  • Bacteria range between 0.2 and 1 micron
  • Viruses range between 0.02 and 0.4 micron
  • Grit – 1 to 5 mm
  • Sand – 0.1 to 1 mm
  • Silt – 0.01 to 0.1 mm

As such, all the above contaminants will be effectively removed when using a Reverse Osmosis water purifier. Let’s attempt listing some of the most common contaminants that reverse osmosis water purifiers can get rid of:

  • Sodium
  • Chloride
  • Copper
  • Chromium
  • Lead
  • Arsenic
  • Fluoride
  • Radium
  • Sulfate
  • Calcium
  • Magnesium
  • Potassium
  • Nitrate
  • Phosphorous
  • Antimony
  • Asbestos
  • Barium
  • Beryllium
  • Cadmium
  • Cyanide
  • Mercury
  • Nickel
  • Nitrates
  • Nitrites
  • Selenium
  • Sodium
  • Thallium
  • Algae
  • Aluminium
  • Amoebic cysts
  • Atrazine
  • Chromate
  • Cryptosporidium cysts
  • Giardia lamblia cysts
  • Manganese
  • Magnesium 
  • Pesticide toxins like Endrin, Heptachlor, Lindane, Pentachlorophenol


From the above exhaustive list, you must have noticed that Reverse Osmosis gets rid of some nutritionally important minerals naturally found in water. These include calcium, magnesium, fluoride, sodium, copper, selenium, and potassium. For this reason, the resulting filtered water is termed as de-mineralized. 

And this is what causes some people to campaign against the use of RO water purifiers. Why on earth should you remove from water all the minerals you need for a healthy body?

In line with this, ask yourself: By failing to purify drinking water so as to benefit from these minerals, what amounts of harmful contaminants am I ingesting?

You see, it remains a matter of compromise. Research has it that the proportion of harmful contaminants to essential minerals in raw water can be much larger than you ever thought. There is therefore no valid reason to drink all the pollutants into your system so that you can benefit from the trace amounts of beneficial minerals.

However, to cater for those enthusiastic about mineralized water, manufacturers introduced the re-mineralization cartridge in RO water purifiers. This adds back the essential minerals that are initially removed from the water. 

Even better, you can easily replenish the missed minerals by eating food rich in these minerals. 

Acidity levels of filtered water

RO filtered water ends up with a pH of about 6-8. When exposed to air, the pH drops to about 5.2, which is more on the acidic side. This should however not scare you. The human body is naturally able to regulate the pH and find a balance of about 7.4. After all, that is what happens when you take acidic drinks like lemon juice.

To wrap it up

It is recommended that you invest in a water purifier, preferably of the Reverse Osmosis type. Having this in your home will save you from most of the water-related diseases and the poisoning effect of the contaminants.