Why do we need a water filter?

Many of our water sources are polluted. Bottled water is not a practical option. They give us more problems in the long run. Good water filters give us several years of service. It is cost effective and dependable.

A big shop offers twenty or thirty different filters, now how do we choose the right one?

A common customer does not have time or patience to study product features. Sellers take advantage of our laziness. Many of the fancy features do not actually improve the quality of water. There is no rocket science behind a water filter. A filter we buy from shop is actually a filter set. There are four or five different filters are inside every filter unit. Sellers usually use the term 'purifier' distinguish the filter unit from the individual filters that goes into it If your source water is not highly polllutted all you need is a sediment filter and one good quality carbon filter. If there is a membrane filter that is more than enough. But no one is interested in selling such a simple unit becuse there is no big money to make.

When a seller says "this is a four stage or five stage filter" what does he actually mean?

Don't think these stages like number of floors in a building. A basic home purifier needs four filters. - a sediment filter, a pre carbon filter, a membrane filter and a post carbon filter. We can call it a four stage filter. Then they may add one extra sediment filter or a UV lamp then it becomes five stage or six stage filter. The picture you see here is a four stage Reverse Osmosis filter.

Can you please explain these sediment, carbon and RO filters?

Ok. Let's see them one by one.


1. Sediment filters: Sediment filters, as mentioned above, are only meant for removing larger suspended particles from water. These filters are first level or primary filters.  Sediment filters are usually made of polymer, cloth like material. PP filter means polypropylene (a kind of nylon) filter. They have pore size around 5 microns. Remember, 5 micron filters are only pre treatment filters. They are useful inside a purifier. We cannot use a sediment filter as a stand-alone unit.

2. Activated Carbon Filters: Carbon is very effective in removing chemicals and most impurities from water. It also gives a very fresh taste to water. Carbon is activated by passing oxidizing gases at very high temperature to create pores in the carbon which substantially increases the surface area to trap impurities. Surface area of one pound of activated carbon is said to range from 50 to 150 acres which makes it very powerful in capturing the impurities. Activated carbon stops impurities in two ways. First it does not allow particles above the pore size to pass through. Secondly, it traps chlorine and other contaminants inside the pores. There are two types of activated carbon:


a) Granular Activated Carbon (GAC) Filters: GAC Filters made by packing lose carbon granules to allow the water to pass through it. GAC filters allow faster water flow. But they are less effective compared to Solid Block Filters.


b) Solid Block Activated (SBAC) Carbon: As the name indicates carbon is bonded together to form a single solid block. These filters provide larger surface area compared to GAC filters. Smaller pore size of SBAC filters allow better filtering.


3. Membrane Filters: Membrane filters the most efficient in water purification. Imagine using a piece of cloth for filtering water. Adding more and more layers of cloth will make it harder for dust to pass through. But we cannot add twenty or thirty layers. But it is achieved in a membrane filter. They roll the membrane around a perforated cylinder. Water has to pass through these layers to come to the cylinder at the center from where there is exit to the next level. There are two type of membrane filters:


a) Ultra filters: These filters are far more compact compared to carbon filters. They are very effective against micro organisms and all other forms of impurities. Water passes through these filters without the use of pressure pump. Thus UF filters are easier to manage.


b) Reverse Osmosis filters: First of all, the term 'Reverse Osmosis' is a big marketing term. American salesmen are famous for enriching the English language by this kind of wonderful imaginations. Technically it is a filter with a more compact membrane. Water does not pass through these filters unless we apply some extra pressure. We put a pressure pump to  do the job.  Now there is another problem; when we push all the water thogh the membrane it can damage and block the membrane. To solve that problem we give a bypass exit and allow some water to run out though it. Thus this filter has two outflow valves. The water passing through the membrane is collcted in the tank and the water coming out through the bypass valve is drained out. With RO filters there is a problem of water wastage. For every one litre of water collected in the tank, three litres are wasted.


4. UV Filters Ultra Violet (UV) light stops the reproduction of bacteria and viruses. These filters are effective only against microorganisms. They do not remove other impurities. We cannot use it as stand-alone unit. However it is very useful in combination with other filters such as carbon or polymer filters.


Apart from the above basic purification methods there are several other technologies used independently or in combination with the above.

Can you give some details of the models that you are offering?

We give mainly UFpurifiers, becaue they are trouble free. Customers can do the maintenance without waiting for a technician. We give RO filters only if the customers insist on them.

Can you give a comparison between UF and RO filters?



Why do we need a water filter?

Many of our water sources are contaminated. Filters are the only practical option to protect us from water borne diseases.



Why do we need a water filter?

Many of our water sources are contaminated. Filters are the only practical option to protect us from water borne diseases.





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