5 Different Types of Water Filters and How They Work

Water filter

People are paying more and more attention to the health of drinking water, and water filters are the best way to obtain healthy drinking water. There are many different types of water filters on the market, but many people don’t know much about common water filtration. Therefore, understanding the types and working principles of the most common water filters can determine which water filter is suitable for you to help you quickly filter different water qualities and obtain healthy drinking water.

What is a water filter?

The water filter consists of a cylinder, a stainless steel filter, a sewage discharge part, a transmission device, and an electrical control part. When the water filter is working, the water to be filtered enters from the water inlet, flows through the filter, and enters the pipe required by the user through the outlet for process circulation. The particulate impurities in the water are trapped inside the filter. Therefore, a water filter is a device that removes impurities, particulate matter, odor, bacteria, viruses, and other harmful substances in the water through screening, adsorption, chemical reaction, sterilization, and other methods.

However, there are many different types of water filters on the market, and their filtering effects are also different. Some filtering effects are more effective than other water filters in removing certain pollutants. Next, let's get to know the different types of water filters.

What are the different types of water filters?

There are five common water filters on the market, each of which can filter different pollutants in the water, as follows:

  • Activated carbon
  • Ion exchange
  • Reverse osmosis
  • Mechanical
  • Ultraviolet

Activated carbon

Activated carbon water filters can reduce chlorine, chloroform, agricultural chemicals, organic matter, sediment, and magnesium.

Working principle: The uneven structure of the activated carbon surface promotes the adsorption of impurities in the water. The water flow with qualified water quality will pass through the pores of the activated carbon, and various suspended particles and microorganisms will be adsorbed in the pores under the action of force.

It can also reduce the hypochlorous acid in the water, thereby replacing the chloride ions and effectively removing the residual chlorine. To ensure the normal operation of the membrane in the reverse osmosis equipment, more and more impurities are trapped outside over time, which will affect the efficiency of the equipment. Usually, backwashing is performed to restore the efficiency of the activated carbon filter. The size of the activated carbon particles also affects the adsorption capacity.

Generally speaking, the smaller the activated carbon particles, the larger the filtration area. Granular activated carbon does not easily flow due to particle formation, and impurities such as organic matter in the water are not easy to block in the activated carbon filter layer. It has strong adsorption capacity and is easy to carry and replace.

Ion exchange

An ion water filter is a device used for water treatment, and its working principle is based on the charge exchange between ions. It usually consists of a resin bed with many tiny particles on it, which have exchangeable ions.

Ion water filters can remove some impurities, minerals, and ions in water, making the water purer. The working process is as follows:

Adsorption: When water-containing impurities pass through the ion water filter, the ions in the impurities are adsorbed by the resin. Depending on the properties of the resin, different ions are adsorbed to the resin particles. For example, a cation exchanger adsorbs positively charged ions, while an anion exchanger adsorbs negatively charged ions.

Exchange: When ions in water are adsorbed to the resin, the resin releases the ions originally present on it and exchanges charges with the adsorbed ions. This is the process of ion exchange.

Flushing: When the ions adsorbed by the ion water filter reach a certain saturation, the resin needs to be regenerated. This is usually achieved by flushing the ion solution to wash away the ions originally adsorbed on the resin and restore the resin to a state where it can be adsorbed again.

Through this cycle process, the ion water filter can remove various ions in the water and improve the water quality.

Reverse Osmosis

What is Reverse Osmosis? Reverse Osmosis (RO) is a membrane separation process in which water is pressed against the membrane surface. Purified water passes through the membrane and is collected, while concentrated water, containing dissolved and undissolved materials that cannot pass through the membrane, is discharged to the drain.

The key requirements of the RO process are that the membrane and water are under pressure and that other materials are pre-filtered to remove suspended impurities and carbon and to remove chlorine (which damages the membrane). Most membranes remove 90-99+% of dissolved impurities, depending on the impurities and the composition of the water.

Reverse osmosis systems remove salts, microorganisms, and many high molecular-weight organics. System capacity depends on water temperature, total dissolved solids in the feed water, operating pressure, and overall recovery of the system.

Working principle of RO membrane reverse osmosis purification

Apply a certain pressure to the water, so that water molecules and ionized mineral elements pass through the reverse osmosis membrane, while most of the inorganic salts dissolved in the water, including heavy metals, organic matter, bacteria, viruses, etc., cannot pass through the reverse osmosis membrane (RO membrane pore size 0.0001 m, virus diameter 0.02-0.4 m, general bacteria diameter 0.4-1 m), so that the pure water that has permeated and the concentrated water that cannot permeate are strictly separated.


Mechanical water filter, also known as pressure filter, refers to the process of filtering suspended solids, insoluble particles, color and taste, and dechlorination in water under a certain pressure through filter media to achieve the purpose of purification.

The working principle of mechanical water filters is based on the principle of physical filtration. It mainly blocks solid particles through a filter element or filter screen, so that particles in liquid or gas cannot pass through, thereby achieving the filtering effect.

Mechanical water filter screens solid particles through a fixed aperture or mesh. When the liquid or gas to be filtered passes through the mechanical filtration equipment, larger solid particles will be retained by the filter element or filter screen, while smaller particles can pass through. In this way, the solid particles in the liquid or gas are effectively separated to obtain a cleaner liquid or gas.

Mechanical water filters have micron levels, and the effects of different levels of filtration are also different. Common micron levels include:

10-micron filter: can remove particulate matter with a diameter of about 10 microns, such as sand, soil, etc.

5 micron filter: can remove particulate matter with a diameter of about 5 microns, such as smaller impurities and particles.

1 micron filter: can remove particulate matter with a diameter of about 1 micron, such as tiny particles and microorganisms.

0.1 micron filter: can remove particulate matter with a diameter of about 0.1 microns, such as smaller particles, viruses, and organic matter.

Ultraviolet light

An ultraviolet water lamp is a common household water treatment system that can remove bacteria, viruses, and some parasites.

Ultraviolet filters use ultraviolet light of a specific frequency (UV-C) to disinfect water, which is safe and environmentally friendly. Its working principle is:

When bacteria and viruses in the water are exposed to ultraviolet light, their DNA absorbs ultraviolet energy, causing structural damage and unable to replicate and reproduce, thereby achieving the effect of purifying water quality.

It is worth noting that ultraviolet filters mainly target bacteria and viruses and cannot remove chemical pollutants such as chlorine, lead, and pesticides. To obtain a more comprehensive purification effect, it is recommended to combine ultraviolet filters with other types of filters (such as activated carbon filters) to create multiple guarantees, so that you and your family can drink cleaner and more reliable water. For more working principles, see How does the UV water filter work?

Which water filter is best for drinking water?

How to choose a water filter? You need to decide which water filter to choose based on your water quality because different types of water filters will remove different impurities and pollutants. The best drinking water filters on the market use a combination of different filtration methods, so you can choose a water filtration system that mixes multiple filtration steps. For example, the ITEHIL reverse osmosis water filtration system, through PP cotton + activated carbon filtration and reverse osmosis filter filtration, it can filter out all harmful substances and obtain healthier and safer drinking water.


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