Type of Water Purifier

There are five major categories of water purifiers, depending on the purification methods they use. The following figure lists these categories :

RO Water Purifiers 
RO water purifiers are the most commonly used purifiers and are based on the principle of reverse osmosis. They make use of the membrane technology to eliminate contaminants such as salts, heavy metals and germs dissolved in water. The following image shows an RO purifier membrane :

The main advantage of using an RO purifier are as shown in the following figure :

Removes impurities such as lead, arsenic, mercury and germs from water 
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Environmental friendly 
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Suitable for hard water 
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Suitable for hard water with high total dissolved salts (TDS) 
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easy to install and maintain 

There are certain disadvantages of an RO purifier such as:

• Removes essential minerals along dissolved impurities 
• Alters the taste of water 
• Wastes large quantity of wayer
• Requires electricity to purify water
• Requires special care and maintenance for it's membrane 

UF Water Purifiers 

UF water purifiers use membranes similar to an RO membrane but with large pores. They remove all germs and bacteria from water but do not remove dissolved salts or solids. They are suitable in homes where the water supplied is not very hard and less dissolved salts. The process of privation in a UF purifier is shown in the following image :

The main advantages of using a UF purifier are as shown in the following figure :

Removes impurities and germs from muddy water 

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Environmental friendly 

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Does not require electricity to purify water 

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Retains the taste and odor of water 

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Easy to install and maintain 

There are certain disadvantages of a UF purifier such as:

• Unable to remove dissolved impurities such as arsenic, lead, nitrates and fluoride 
• Ineffective as compared to an RO water purifier as it cannot block dissolved salts and solids 
• Good only for water with low TDS 

UV Water Purifiers 

UV water purifier use ultraviolet rays to kill all germs,  bacteria and microbes dissolved in water. A small mercury lamp is placed inside the purifier, which produces high frequency short wave UV radiations. When water passes through this element, it is exposed to the UV light which kills all the living organisms. 

Separate filters then remove the dead germs. 

UV purifiers are used in residences, breweries, water stores,restaurants and municipalities. 

The following image shown the working of UV water purifiers:

The main advantage of using a UV purifier are as shown in following figure :

Removes viruses, bacteria and germs from water 

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Environmental friendly 

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No chemicals added to wayer

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Retains the taste and odor of water 

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Easy to install and maintain 

There are certain disadvantages of a UV purifier such as:

• Unable to remove dissolved impurities such as arsenic, lead, nitrates and fluorides 
• Requires electricity to purify water 

Gravity Based Water Purifiers 

Gravity based water purifiers are based on the principle of gravity. The water flows from a higher compartment over the filters to a lower compartment. They do not require electricity and use either chemical based, UF based or ceramic cartridge based filters to purify water. 

The following figure shows the parts of a gravity purifier :

The main advantages of using a gravity based purifier are as shown in the following figure :

Removes impurities and germs from muddy water 

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Environmental friendly 

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Does not require electricity to purify water 

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Suitable for soft water 

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Portable and easy to install 

There are certain disadvantages of a gravity based purifier such as:

• Unable to remove dissolved impuri+ies such as arsenic, lead, nitrates and fluorides
• Ineffective as compared to an RO water purifiers as it cannot block dissolved salts and solids 
• Good only for water with low TDS

Activated Carbon Water Purifiers 

Activated carbon is carbon with a positive charge added to it. When water flows over it, the negative ions of contaminants get attracted to the surface of the activated carbon filter. 

Activated carbon water purifiers can remove volatile organic compounds, pesticides, herbicides, chlorine and other chemicals found in tap water. This makes the water safe to drink. 

The following images shows the license of purification in an activated carbon water purifier:

The main advantage of using an activated carbon purifier are as shown in the following figure:

Removes volatile organic chemicals, radon and chlorine 

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Environment friendly 

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Eliminates bad order and taste 

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Cost effective 

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Does not require electricity to purify water 

There are certain disadvantages of an activated carbon purifier such as:

• Unable to remove dissolved microbes and impurities such as arsenic, lead, nitrates and fluorides 
• Ineffective as compared to an RO water filter as it cannot block dissolved salts and solids 
• Requires frequent filter changes