Different kinds water purifiers, how water purifiers work
There are many different kinds of water purifiers available in India today. Water purifiers can be from just a simple water filter with filter cartridge element to the more advanced water purifiers using membranes for water filtration followed by sterilisation with UV filter.
We explain how different types of water purifiers work and once you understand how water purifiers work it is easy to decide on which type of water purifier to buy.
Cheap and best water purifier in India
For most houses in India supplied with Municipal or Corporation water, just a simple cheap water purifier with a cartridge is the cheapest and best solution. Cheap water filters are just very fine sieves through which when the water passes through, solid particles bigger than the size of the sieve holes or pores gets trapped and filtered out of the water.
Modern day water filters using the sieving method must have evolved from the Middle Ages, when pieces of cloth were used by people to filter their drinking water from river, pond, well or rain water. During this filtration process through cloth, when the cloth got dirty and clogged, they would have rinsed the cloth clean and reused it. The same way most of these cheap water filter cartridges can be washed and reused.
Pore size of water filter
Water filtration still depends on passing the water through fine pores or holes, only now the pore sizes have become very much smaller. The size of the pores or holes in a cloth is very large when compared to modern day filter media. While the pore size of the cloth would be measured in fractions of a mm or millimeter (1/1,000 or 0.001 Meter) a modern day water filter pore size is measured in Microns or a micrometer normally written as μm = 1 by a million or 0.000001 Meter. That is about a thousand times smaller the pore size of plain cloth.
The smaller size of the pores means that it is more difficult for the water to pass through them, hence the water needs more pressure to pass through the smaller pores. In the case of gravity water filters the pressure is low, which means the flow of water will be less, and so in gravity water filters the water is filtered almost drop by drop and it will take a long time to filter water. When the pores of the water filter are small, more dirt gets filtered out, and hence smaller pore sized filters gets clogged and blocked more easily.
Activated Carbon in water purifiers
Activated Carbon in water purifiers removes many dangerous organic chemicals like pesticides which may be present in the water. Activated Carbon in water purifiers also removes chemicals in water which cause water to taste bad. So it is good to have an activated carbon water filter purifier for drinking water
Activated Carbon is an extremely porous material that attracts and holds on its surface harmful chemicals by a process known as adsorption. Humans knew the process of filtration of water through charcoal for more than 5000 years. The use of charcoal beds for filtration of water has been discovered in ancient Egyptian and Indian Civilisations by archaeologists. Activated Carbon used today is the same type of charcoals used then, but now the carbon is activated by high temperature steam treatments. ......More from our page on Activated Carbon for water purification
Membranes in water purifiers
Membranes in water purifers are one of the best ways to purify water for drinking. Nature uses membranes to purify water. The coconut tree purifies dirty ground water using membranes in its roots, and sends up the purified water with the addition of nutrients, to its tender cocoanuts to give us that refreshing tender coconut water. Membrane water purification technology that we use today uses membranes similar in properties to the membranes in the roots of a coconut tree. We use synthetic membranes made out of very thin sheets of a plastic material which have very fine holes or pores. The pore sizes are different in different types of water purification membranes. Membranes are classified according to the pore size of membranes as Micro-filtration membranes MF, Ultra-filtration membranes UF, Nano-filtration membranes NF and Reverse Osmosis RO membranes. The pore size of RO membranes are the smallest and can filter out dissolved chemicals out of water and thus even convert salt water into fresh water. ......More from our dedicated page on Membrane Water Purification
Which kind of water purifier is best in India
Selecting a water purifier in India for house depends on the quality of water you get in the house. As explained above there are different water purification technologies and selecting which type of water purifier is best depends on the type of water or impurities in water that is there in the house. Below we will explain how different kinds of water purifiers work to help in deciding which kind of water purifier is best in India.
Multi stage home water purifiers and how they work
Modern home multi stage water filter purifiers combine different kinds of water purifiers into one unit. The different stages of a multi stage type of water purifier are as follows:
- The first stage of water purification in all home water purifiers is to get rid of the larger solid particles like mud and dirt with a sediment filter. Pore size of the sediment filter is usually 20 microns. If the water contains a lot of mud or other larger particles, then this cartridge element becomes blocked quickly. It can be removed, cleaned by jetting with water and reused. It is like a cloth being reused after rinsing.
- The second stage in a home multi stage water purifier is a finer filter with pore size varying from 5 microns down to 1 micron or even less. These fine pore water filters removes larger germs like parasites. The smaller the pore size, the more efficient it will be in removing microbes and germs from water. The disadvantage of having very small size pore water filter is that a higher water pressure will be required to drive the water through. If the pressure is not sufficient, the water coming out of the filter will be very slow. Since multi stage home water purifiers usually have a germ killing devise like UV (Ultra Violet) at the last stage of the multi stage water purifier, any germs passing through the finer filter will be killed later. So a compromise is made by having a 5 micron second stage filter cartridge.
- The third stage in a multi stage home water purifier is an Activated Carbon water filter in the form of an activated carbon block cartridge element. The active carbon water purifier adsorbs toxic organic chemicals like pesticides. It is very important to understand that there are many qualities of activated carbons and some may not be very efficient. Also the activated carbon has limited capacity to hold harmful chemicals, so make sure it is changed at the recommended intervals. ...More about Activated Carbon from our page on Activated Carbon
- The fourth stage will normally be a germs killing devise, usually a UV water purifier which has UV light to kill any remaining germs in the water. Some water purifier manufacturers call UV water purification as 'e-boiling' - See our page on Ultraviolet UV water filters. Other methods in the final stage to kill germs could be by passing water through special media which release chlorine, or through media with nano-silver particles.
The filtration stages 1 to 3 described above can be as separate filtration units one after the other or it is possible to combine all stages into one filter cartridge by having the different media one under the other, so that the water flows through each media.
As the filter removes the particles from the water, their pores are getting blocked and water pressure is being lost. This means over time the flow out of the filter becomes slower and slower until it almost stops. The time it takes for the filter to become blocked depends on how much dirt there is in the water. Most water purifiers have replaceable filter elements called cartridges, and it is a simple procedure to change cartridges. Once cartridges are replaced, the flow will be restored.
Home water purifiers with RO
Home water purifiers with RO are now the most popular water purifier in India. RO or reverse Osmosis water purifiers use RO membranes to purify water. There are other types of membranes for water purification but RO water purifier is the most popular in India. Other types of membranes in water purifiers are Ultrafiltration UF membrane water purifiers which can remove all bacteria, virus from the water but not any dissolved chemical impurities in water. Then there is Nanofiltration NF membrane water purifiers that removes everything that the UF water purifier removes (bacteria and Viruses) plus it also removes larger molecule salts in water, like Calcium and Magnesium and some of the Heavy Metal salts.
Salts like sodium Chloride remain in the water in a NF water purifier. NF water purifier is capable of softening water. Finally there is the Reverse Osmosis RO water purifier which removes all impurities in water – virus, bacteria and all salts. So RO water purifier is the best type of water purifier available in India for drinking water.
How to buy Water Purifiers in India
The best way to buy Water Purifiers in India is to first look at all models of Water Purifiers available online at the leading online Retailers in India. For example on the online webpage of All Water Purifiers available in India on Amazon.in, you will find the full range of Indian Water Purifiers complete with their best discounted price and full specifications. This is great information, and you can decide on which model of water purifier to buy. With the model of water purifier you want to buy finalised, you can go to local shops to try and find the model of water purifier you have chosen and see if you can get at similar price of that at Amazon.in. In most cases the price from Amazon will be cheaper, because they buy in bulk from the manufacturers direct and they sell huge volumes because they are the world's largest and most trusted online retailer. If you buy from Amazon, they will arrange to have the water purifier installed in your house, usually free of charge.
Warranty and other facilities offered through Amazon are usually better than what you can get from local agents of water purifiers.
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