Part I - Summary of Water Filters In India

We cannot live without water, and the water we use has a significant influence on our health and well-being.  Other than cities and towns, most people in India depend on ground water or rivers for their water needs.  Use of water filters is increasing, but they are not understood well.  Marketing ploys by the Filter manufacturers tend to be biased, and there are no BIS standards to adhere to.

With all these complexities, there are very few unbiased, independent analyses of water purifiers and filters in India.  This blog is an attempt to demystify the techniques and buzzwords that Filter producers use, and portray in black and white what is really needed.

Depending on the source of our water (municipal supply, river, borewell, tanker etc), it may contain micro-organisms (bacteria, viruses etc), solid contaminants (calcium, magnesium...) and potentially heavy metals (lead, arsenic etc) among others.

Most Water Purifiers use a combination of the following techniques for purification:

• Filter (Activated carbon, granular carbon, carbon block are popular) for removing oils, solids and most bacteria
• Reverse Osmosis - using a semi-permeable membrane to filter out solids, metals, salts and bacteria
• Ultraviolet disinfection - using a UV lamp (8-20W) which basically re-arranges the DNA of bacteria so that it cannot replicate itself
• Cation Exchange Softener - to eliminate Calcium and Magnesium
• Chemical Purification (using Chlorine, Iodine etc ) to disinfect

Let us look at our choices in the market - major brands are AquaGuard (owned by Shapoorji Pallonji), PureIt (UniLever), Kent and Tata Swach.  All except Kent are owned by large companies with deep pockets. Other companies that manufacture water purifiers include Philips, Godrej, Usha, Jaipan, Kenstar and Whirlpool.

AquaGuard has the most extensive range - most of their models use combinations of activated carbon filter and UV.  More recent models of Aquaguard have been incorporating RO in response to Kent.  UniLever entered the market in the last decade using Chlorine and activated carbon filter as their core technique. Kent entered the market with models that use Reverse osmosis, and emphasized taste as their USP. TATA is the latest entrant, targeting the bottom of the pyramid.

Let us look at positives and negatives of each technique.

None of them can kill viruses, as a National Institute of Virology study indicated recently. Another recent article in The Hindu states that even water purified by water purifiers may not be safe, hence the need to test the water regularly. 

Most filters are effective against bacteria, but not viruses and spores.  So you remain vulnerable to viral diseases, should the water be home to such viruses.  

Chlorine has been demonstrated to be a very effective disinfectant, but it leaves a bad taste and smell behind. For a long time most city municipal water agencies used Chlorine to disinfect the water reservoirs, and gradually gave way to UV based disinfection.  UniLever's PureIt filters use a technique which releases Chlorine slowly into the stream, and the later models use an additional step to remove Chlorine.  Most PureIt Filters use no electricity just because activated carbon filters and Chlorine tablets do not require power.

For Ultraviolet disinfection to be effective, a certain minimum exposure, dosage and residence time are needed to re-arrange the DNA of bacteria, and neutralize them.  In most cases,consumers just open the tap full speed thus exposing the water to minimal time for UV to take effect.  Additionally, some of the commercial UV lamps are low in intensity (8-10W) so I doubt if such treatment affects the micro-organisms.

Activated Carbon and other granular carbons have been proven to be very effective in adsorbing contaminants and bacteria.  But at times, during transportation or handling, the carbon blocks may break, and if that happens - water may just pass through unfiltered. Also, if the activated carbon is not replaced regularly, it may re-release the contaminants back into the water.

So, back to the fundamental question, which is the Best filter out there in the Indian Market?

If you see the ads of most of these companies, most of them use the words "As safe as Boiled Water" in their ads. Boiled Water is their benchmark to which they compare their own effectiveness.

Water raised to 72 deg C kills almost all known bacteria AND VIRUSES.  At boiling temperatures (100C), one can be rest assured that no micro-organisms are left in the water. This has been demonstrated by several laboratories.

But boiled water cannot remove solid contaminants, heavy metals etc which remain.

Our recommendation is to use a simple activated carbon filter (any company is fine) and then boil the water so as to ensure that all micro-organisms are rendered ineffective.  If you think this is tedious, pretty much most of the commercial filters do a mediocre job.  There are no standards  yet, so these products are not really regulated, nor are there Bureau of Indian Standards (BIS)  yet.  This is one market where spending big bucks does not correlate to getting the best. Our opinion is also that Reverse Osmosis filters are overkill, waste too much water, consume a lot of electricity, and tend to be expensive.

Other Related Posts:

Part 2 - Reverse Osmosis Water Filters

Part 3 - Review of TATA Swach

Part 4 - UltraViolet (UV) Method of Water Disinfection

Upcoming Posts:

Maintenance and Service of Water Filters

Comparison of Various Brands