All about water purifiers

Is your tap water safe or do you need to purify it? Or should you just buy bottled water? How do you decide? Here is a quick guide to water quality and water purifiers.

Sharad and Sheetal Agarwal, a young couple living in South Bengaluru spend Rs. 500 and above on drinking water every month. They bought a water purifier from a reputed company three years ago but felt it wasn’t safe after frequent gastro problems.

“Our building receives water from tankers mainly and we aren’t really sure of the source and how effective our purifier is, so we felt buying 20 litre Bisleri bottles was a safer option,” Sheetal says. The couple plan to acquire a new water purifier but are not sure which system would give them foolproof protection against contamination and water borne diseases. Terms such as  activated carbon, reverse osmosis, ozonisation, etc., can also be confusing in this case.

water purification

Purified water? Pic: Meera K.

Like the Agarwals, several families in Bangalore wonder what to look for when buying a water purifier that is really effective against chemicals and contaminants than just going by the tall claims of manufacturers. Citizen Matters approached S Ramani of Consumer Association of India, to find out how to buy an effective water purifier for your home. We also got some inputs from India Water Portal, an initiative of Arghyam, an NGO working in the water sector.

Test Your Water

If you really want to be sure of the quality of water you are drinking and be thorough in your pre-buying research, then the first thing to do is to test the water your receive at home, says Ramani. The process isn’t difficult. You can contact water testing labs in Bangalore such as  Essen Labs in Malleswaram (080-23341230/1567) and give them two litres of water sample in any clean bottle washed with hot water. They conduct a total of 33 tests to check for chemical, bacterial contaminants and give you the report in 12 working days. The cost works out to about Rs. 993. You could also contact Ion Exchange in Indiranagar or Aqua Diagnostics in Hosur Main Road for the same.

Click here for a list of Karnataka state recognised private labs. India Water Portal has also compiled a list of water quality testing labs in the city. You can find the list here.

Ramani says concerned citizens should “keep the lab test results in mind when shopping for a purifier.” He further adds that “there are ads for a portable Water Test Kit, around Rs. 50 per test. (One such possible source is Himedia Laboratories). These kits claim quick results for chlorine, lead, nitrate, nitrite, two pesticides, pH, and total hardness. These also claim to test for bacteria but may require waiting 48 hours. This may be a good test if you are in the habit of buying large water bottles for home use.” If you find the tests expensive, Arghyam can do indicative tests for free, post which you can take the samples for lab tests if necessary.
Choosing the right filter

Once you get the test results, find out what is the desirable water quality. According to Arghyam, the common contaminants in Bangalore’s drinking water supply are bacteriological contaminants, nitrate and Total Dissolved Solids (TDS). Bacteria is usually found in water from Cauvery and borewell water, while nitrate is mainly found in borewell water. TDS too is found in borewell water supply.

For, Indian standards for drinking water – specification (BIS  10500 : 1991), click here.

While no bacteria is permitted in drinking water, as per the Bureau of Indian Standards (BIS) drinking water specification, the Nitrate permissible limit is 40 parts per million (PPM) and TDS is 500 PPM. According to a report in Down To Earth, a science and environment magazine , a BIS revision started in 2003 introduced limits for 18 pesticides and four disinfection byproducts. However, it is still in the draft stage.

In Bangalore, many people buy Bisleri or Kinley or other branded bottled water for daily use. All packaged drinking waters are to be sold only with ISI certification mark. This scheme is a certification of the processes followed by the manufacturer and checked by BIS. These are to be strictly followed by the manufacturers.

Failure to follow will lead to cancellation of licence. But each and every bottle is not and can not be tested by BIS, says Ramani. Market samples should be tested by Health Department officials according to PFA rules. Ideally, an NGO should take up such studies in the interest of public. And there should be support from the public health departments, BIS and public.

Once you get your water tested, the next best thing is to find out the kind of technology you need to remove contaminants from water. “The water purifier needs to remove undesirable chemicals, materials, and biological contaminants from raw water and make it fit for human consumption. In general, the methods used include physical process such as filtration and sedimentation, biological processes such as slow sand filters or activated sludge, chemical process such as chlorination and the use of radiation such as ultraviolet light,” Ramani adds. What the purification process does is reduce the concentration of particulate matter including suspended particles, parasites, bacteria, algae, viruses, fungi; and a range of dissolved and particulate material derived from the surfaces that water may have contacted with.

Technologies Available

Activated carbon: This is a form of carbon (usually charcoal) that has been processed to make it extremely porous providing large surface area for adsorption or chemical reactions. Activated carbon filters use granular carbon or blocks of powdered carbon that can remove pesticides, chlorine, and other chemicals found in tap water. It is a more commonly used technology and according to the third edition of WHO’s guidelines for drinking water quality, technologies such as  activated carbon and ozonation are most suitable for removing pesticides and other organic chemicals, says a report in Down To Earth.


Reverse Osmosis (RO): This is basically filtration at molecular level. Mechanical pressure is applied to an impure solution to force pure water through a semi-permeable membrane. It is reverse because under normal osmosis, pure water moves into the contaminated water without any pressure. Reverse osmosis is theoretically the most thorough method of large scale water purification available, although perfect semi-permeable membranes are difficult to create. Unless membranes are well-maintained, algae and other life forms can colonise the membranes. Secondly, this is a very slow process. RO is required in your home if the Total Dissolved Solids (TDS) exceeds the upper limit, according to the India Water portal. RO is also suggested if you live close to an industrial area and your water may possibly be contaminated with sewage, pesticides, heavy metals, industrial effluents.


Always read the manufacturer’s claims carefully: Even within a specific brand, contaminant removal claims may vary. Match the filter to the contaminants in your water.

Consider total long-term costs. Filter replacement can cost low or set you back Rs 3000 or more. So find out how frequent changing candles or membranes and maintenance is. RO filters for instance cost upwards of Rs. 8000 and need to cleaned and examined regularly. The pre-filters and RO membranes also need to be changed. It is also said to lead to a lot of wastage of water.

Life span of system: Theoretically, the system should work as long as proper maintenance is done. There are rarely any moving parts for wear and tear. The additional expense need to be kept in mind is the Annual Maintenance Cost, the cost of consumables like filter candles, cartridges should be included.

Good old boiling: If you find that buying a water purifier with the requisiste levels of purification costs too much and you cannot afford to spend on packaged drinking water as well, then a good measure is to get an inexpensive system with simple filtration and boil that water, says Ramani.

Rain Water Harvesting (RWH): As the India Water Portal points out, RWH is a useful permanent solution if your source of water has unacceptably high levels of TDS or hardness. More information here and here.

Ultra Violet Purification: This method is used mainly for disinfection and to make water containing any disease causing micro-organisms safe for drinking. Passing ultra violet rays makes these micro-organisms unable to reproduce. Usage of iodine, chlorine and plain and simple boiling water also achieve similar effect, Ramani adds.

Ion-exchange filters: This is used to remove hardness in water. Ion-exchange filters can remove iron, lead, copper, barium, radium and nitrates and are usually integrated into the water purifier along with other methods.

According to Ramani, the main purification techniques are boiling, filtration, disinfection, pH adjustment and turning  hard water soft using ion exchange resins. The water purifiers available in the market usually integrate some of these techniques. Most of these mainly start with filtering to remove the dissolved solids and use Ultra Violet (UV) rays to reduce the threat of bacteria. 
Testing your purifier

Most manufacturers come up with tall claims about their product. How true are these? For example,  we often hear in ads that Product X has been certified by the Indian Medical  Association. How true are most of these claims?

According to an article in Down To Earth, the Centre for Science and Environment, Delhi, checked a certificate issued by the Indian Medical Association (IMA) to popular water purifier manufacturer Eureka Forbes in 2004 and found out  that the IMA does not really test the purifier before issuing the certificate.

The standards for drinking water quality are typically set by governments or by international standards, says Ramani. “These standards will typically set minimum and maximum concentrations of contaminants for the use that is to be made of the water.” he adds. The Bureau of Indian Standards (BIS) does have standards for some water purifiers such as  UV filters and candle filters.  But we understand that these standards were developed between 1979 and 1999, when it was believed that water purifiers were meant to remove only bacteriological contaminants.  Besides, these standards only apply to water that is free of chemicals and suspended matter. The sought after RO  systems are also beyond  the pale of standards. 


( BIS  10500 : 1991 )


  1. Sejal Parikh says:

    I personally would never recommend anyone RO systems solely because of the huge water wastage associated with it. It almost wastes as much as water that it purifies.

  2. Sejal Parikh says:

    Another issue I have observed with RO systems is electricity wastage. I think it needs to be kept powered on all the times, unlike other types of water purifiers.

  3. Meera Iyer says:

    I’m surprised you haven’t mentioned fluoride contamination. Fluoride levels in water are very high in many parts of Karnataka. Is the situation different in Bangalore?

  4. Madhan says:

    > Another issue I have observed with RO systems is electricity wastage. I think it needs to be kept powered on all the times, unlike other types of water purifiers.

    I don’t think this is the case. Once the 10 ltr holder fills up, we switch it off.

  5. Madhan says:

    > I personally would never recommend anyone RO systems solely because of the huge water wastage associated with it. It almost wastes as much as water that it purifies.

    Agree with you, but no other purification system works for high nitrate and TDS content 🙁

  6. Girish says:

    Hi, first of all I like your article. thank you for a detailed article.

    I have a request, i tested water which i use for home(its from bore well). I got it tested all the minerals are good except high NITRATE content.

    1. The person in the lab says RO is the only means to get rid of this.
    Is this true, because i read in your article that ion-exchange filters get rid of it.
    If ion-exchange filters get rid of it can you let me know what manufacturer models support it? (I have real hard time talking to sales persons 🙂 )

    2. If ion-exchange does not get rid of nitrate, and if only RO does. I am concerned about using RO as it is not Natural and it will take out all minerals which, would have harmful effects when consumed over long run.

    Please help me find a solution …

  7. Jacqueline Rose says:

    Hello there,Water treatment ought not be a substitute for an appropriately designed, constructed, and kept up water supply.Counteracting pollution is a standout amongst the most immediate methods for diminishing health risks from drinking water.Contingent upon the seriousness of contamination,it might be important to supplant your wellspring of drinking water by developing an option water supply or acquiring bottled water.Some of these options can be unreasonable and badly arranged,so it is critical to have your water tested frequently and stay educated of community water quality issues and choices.Good day.
    household water treatment

  8. Emily Reed says:

    Since every purification technology evacuates a particular sort of contaminant,none can be relied upon to uproot all contaminants to the levels needed for critical applications.A well-designed water purification system utilizes a blend of purification innovations to accomplish final water quality.Each of the purification innovations must be utilized as a part of a fitting sequence to advance their specific evacuation abilities.

  9. davidvilla says:

    The primary brand of best water purifiers presented in the business sector, Livpure is an easily recognized name today in the Indian market. So I suggest you to buy Livpure ro uv water purifier.


Leave a Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Similar Story

Under the scorching sun: Heat stress takes a toll on healthcare workers in Chennai

Despite experiencing heat-related health issues and high workloads, nurses in Chennai receive no support to brave extreme heat conditions.

On March 3rd, Primary Health Centres (PHC) in Chennai conducted the annual Pulse Polio Immunization campaign for children between the age group of 0-5 years. To ensure no child is missed, the Urban Health Nurses (UHN) made door-to-door visits on March 4 to administer polio drops.  While the initiative garnered praise from all quarters, the tireless efforts of health nurses who walked kilometres under the scorching sun, went unnoticed. On March 4, at 2.30 pm, Meenambakkam and Nungambakkam weather stations in Chennai recorded the maximum temperature of 32.2 degrees C and 31.4 degrees C. However, as the humidity levels were…

Similar Story

Delayed upgradation of hospitals in Mumbai’s suburbs; patients rely on private care

Despite having allocated funds to upgrade suburban civic hospitals, BMC has not been able to redevelop them on time.

When Sangeeta Kharat noticed a lump near her neck, she sought treatment at MT Agarwal Municipal Hospital, Mulund, near her residence. Doctors diagnosed her with thyroid nodules, an abnormal growth of cells on the thyroid gland, and referred her to Lokmanya Tilak Municipal Corporation Hospital at Sion for further treatment. Sangeeta's son, Rajan, initially opted for treatment at Sion Hospital. However, due to the distance and frequency of trips with his job, they decided to switch to a nearby private hospital despite higher costs. Rajan said, " If the MT Agarwal super-speciality hospital had been available, we wouldn't have needed…