Water, which is so essential for life, also happens to be a good solvent. It has a tendency to dissolve substances that comes in contact with it. These could be chemicals and pollutants which can be toxic if consumed. Water also contains a plethora of organisms like viruses and bacteria, which if ingested, can cause water borne diseases. Though the tap water that you receive in your home is purified at source, it could still get contaminated while it is being transported to your house through pipelines, tankers etc. Impure drinking water can cause a number of serious illnesses. According to UNICEF (India), water-borne illnesses like diarrhoea and worm infections are the two major health conditions for Indian school children that affect their learning abilities. In India, there is extensive natural occurrence of arsenic and fluoride in groundwater - both harmful chemicals. Boiling water destroys pathogens but cannot eliminate dissolved solid and chemical impurities. A water purifier that ensures safe drinking water is therefore a must.
There are various types of domestic water purifiers for households available in the market and their cost can range from Rs 1,000 to over Rs 50,000 or more based on the technology used. There are a number of different types of water purifiers available today. Each type addresses specific needs, and there's no "one size fits all" water purification method. For this reason, you first need to know what the different types of water purifiers do, and then match the various benefits of these purifiers to your own specific needs. The popular water purifiers available in the market may use a combination of the below techniques for purifying water.
Here the water is purified by passing it through a candle with very minute pores. Any impurity that is larger than the pores get blocked out. However, minute organisms like viruses may still pass on to the clean side. Some candles also use activated carbon to remove chemicals like chlorine. This is by far, the cheapest purifying technology and does not require electricity. So if cost is your major concern and if you are looking at a minimum filtration of foreign particles from water, this may be your choice. On the downside, these filters are not so effective against all chemicals and microbes. The water thus obtained may still need boiling to kill the microbes. The candles need to be cleaned up frequently as clogging of pores due to impurities could slow down the filtration and make it ineffective. They need to be replaced frequently as well.
These purifiers use activated carbon filters. When water is passed over the activated carbon surface, the contaminants are drawn to the surface of the carbon filter. Lower the flow of water, more effective will be the purification. It is effective is removing the organic compounds, chlorine, pesticides and several other manmade chemicals to a great extent. It also reduces chlorine and can alter the taste and odour. Most water purifiers combine this technology along with others like UV filtering to supply purified water. Electricity is not a requirement for water filters that uses only Activated Carbon filtering. The activated carbon filters may not be as effective as UV filters against microorganisms and need to be replaced frequently to ensure proper water purification
In this technique water is exposed to UV rays that kill almost 99.99% of the harmful organisms present in it. It does not alter the taste, odour or the pH balance of water. Ultra-violet or UV purification destroys all pathogens by changing their cell structure. UV purifiers also usually combine filters like carbon filters. In this method, a lamp is used to create UV rays like those caused by the sun. These purifiers do not change the chemical composition of water, and hence cannot be used in areas with "hard" water from tube-wells or bore-wells. This method is ideal for areas with "soft" water like that from rivers or lakes, with a TDS level of less than 500mg/litre. In India, a number of leading brands have purifiers with this technology, including Aquaguard and Kent. Most filters combine the UV technology with activated carbon to remove the chemicals as well. The UV filters work on electricity and require running water. Starting prices of UV technology based water purifiers begin from Rs 4,000. It requires timely servicing to ensure that the UV bulb and the filters (if used) are replaced on time. Know more on Ultra-violet purifiers: (Understanding UV technology)
These are more affordable than UV water filters and can be purchased in a budget of around Rs 2000. This technique uses chemicals like chlorine tablets for purifying the water. These do not require electricity and should be your choice if you stay in a locality where power cuts are common. Some models can be even serviced at home by changing the chemical tablets at regular intervals. On the down side, the taste of the water could get altered based on the chemical used for treatment.
This could be the most expensive technology for domestic water purifier. A semi-permeable membrane is used for purifying the water. RO process not just eliminates microbes and harmful chemicals, but can also improve the taste and odour. RO based purifiers do not require electricity or continuous supply of water for its functioning. It could be your choice if you live in an area where hard or turbid water is very common. The price range for these filters starts from Rs 14,500 and can go upwards of Rs 25,000. The servicing is crucial as water quality may be affected drastically if the quality of the semi-permeable membrane goes down. However, RO filters may also filter out essential minerals present in water. There are RO filters now available, which claim to retain essential minerals after filtration. These use a combination of techniques like rice husk, silver particles, positive charge technology etc. to purify water. Most of these low cost water purifiers run without electricity and do not require continuous water supply. Know more on (Reverse Osmosis) purifiers: (Understanding Reverse Osmosis technology)
Purifiers can be manual or electric. Purifiers that use Reverse Osmosis or UV filtration usually are electric water purifiers. If you stay in a region with frequent power cuts, a manual water purifier may be a better bet for you than an electric one. Electric filters are also usually more expensive than the non-electric manual ones. Electric filters use pipeline water and usually cannot be used to store water. On the other hand, electric filters are convenient and ensure continuous safe drinking water. A lot of manual filters use activated carbon and sediment filters to purify water. These manual filters can also be used for drinking water storage. Some of other manual filters are fitted directly to the tap. These water purifiers usually use a resin filter for water purification. Storage water purifiers may need more space. On the other hand, electric water purifiers too need a dedicated space for purification. Hence, take space and area available into account when you choose a purifier.
A steel construction is safe, long-lasting and hygienic. A plastic build also ensures safety, does not corrode and is durable. On the other hand, aluminium if used in a purifier can react with salts and minerals in the water, producing harmful chemicals.
There are several certifications and standards that indicate and govern the quality of the water purifier. Indian standards include the IMA or Indian Medical Association certification. Some of the stringent international certifications include the USA EPA (Environmental Protection Agency) test, the ISO (International Organisation for Standardisation) certification, the non-profit NSF (National Sanitation Foundation) and Gold Seal from WQA (Water Quality Association).
Remember that your water purification needs will depend upon prevailing water quality in your region. The ideal water purifier must not only destroy all pathogens but should also filter out all the chemical and other impurities such as excessive minerals in the water in your region. Therefore, the purifier that works great in one city may not be the best solution for another one. Hence, it is crucial that you select the right water purifier that ensures safe drinking water for you and your loved ones.
Finally, do ask yourself the following questions before you select a water purifier for your home