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Reverse osmosis is the key principle behind RO water purifiers. Water from higher TDS (total dissolved solids) level – that is, very hard water – is transferred to the lower TDS level through a filtering membrane. RO technology uses high pressure to push water through an extremely fine filter or membrane. The holes in this membrane are as small as .0001 microns. They remove dissolved salts along with pollutants and other physical contaminants including virus, and harmful metals, minerals, bacteria and microorganisms. Most of the RO purifiers also comprise of TDS controllers (to adjust the TDS level). The filter is kept clean by flushing the separated contaminants so they drain away.

In the quest to live healthier lives, many people have turned to water filters. Some water filters fit into pitchers to provide clean drinking water. Some filters attach to faucets and filter water as it flows out of the tap, and still others filter water as it enters a house so that all of the water in the home is filtered.


What you need to know before buying a water purifier

Water being the most vital element of our life, its purity should be accorded the highest priority by each of us. Water is our Life Line. Many diseases in the third world are either water-borne or due to contaminated water. Unlike the western countries where tap water is safe for drinking, the water that comes through taps in the developing world...

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Design

Purification Type
EAT Filter

The revolutionary 'EAT Filter' with the unique Electro Adsorption technology (EAT) has positively charged iso nano fibres with powdered activated carbon that gives you the power & benefits of 4 filters in one physical filter.

HD Green RO

The new space-age high definition Green RO membrane of Dr. Aquaguard Magna is designed for superior performance to ensure high water recovery and retention of natural minerals. Unique Green RO technology membrane removes excess TDS, blocks dissolved impurities and chemical contaminants, while retaining essential minerals in the drinking water.

HD RO

The new space-age high definition RO membrane of Dr. Aquaguard Magna is designed for superior performance to ensure high water recovery and retention of natural minerals. Unique RO technology membrane removes excess TDS, blocks dissolved impurities and chemical contaminants, while retaining essential minerals in the drinking water

NXT HD RO

The new space-age high definition RO membrane of Dr. Aquaguard Magna is designed for superior performance to ensure high water recovery and retention of natural minerals. Unique RO technology membrane removes excess TDS, blocks dissolved impurities and chemical contaminants, while retaining essential minerals in the drinking water.

NXT HD RO Water Purifier comes with NextGen LED Display, Intelligent Alert Interface

RO

Reverse Osmosis

RO+UF

Reverse Osmosis & Ultra Filtration

RO + SCMT

Silver chraged membrane technology

UF

Ultra Filtration

UV

Ultra Violet

UV+RO

Ultra Violet & Reverse Osmosis

UV+RO+UF

Ultra Violet, Reverse Osmosis & Ultra Filtration

UV+RO+UF+Minerals

Ultra Violet, Reverse Osmosis, Ultra Filtration & Minerals

UV+UF

Ultra Violet & Ultra Filtration

Purity Indicator

Constantly senses, measures and shows the quality of input and output water.

Advanced Voltage Fluctuation Guard

Protects your purifier from sudden voltage fluctuation ranging between 165 and 280VAC

Unique Intelligent Indicator

Alerts you 15 days before life of the Germ kill Kit gets over.


Purification

Recommended for
High TDS (Borewells)

Water sourced from borewells with high TDS (Salty/Khaara/Brackish Water)

Low TDS (Rivers, Lakes)

Water from rivers & lakes having low TDS, which does not taste salty. Municipal/Corporation/Sweet tasting water

Filter Cartridges
Biotron Cartridge

It magnetizes water and de-culsters water molecules to make the water more "bio-available" by unlocking the nutrients in water, promising you the healthiest water.

EMLE

Prevents scaling of dissolved salts on the surface of the membrane and hence enhance both membrane life and performance.

HCCB (Hybrid Carbon Chemi Block) Cartridge

Removes excess chlorine, bad odour, colour, and organic impurities. Also eliminates new age contaminants like heavy metals, chemicals and pesticides.

HD Filter Cartridge

Removes fine particles like dust, dirt, mud and sand.

Mineral Cartridge

Enhances the taste of water by removing dissolved gases like VOCs. It also increases calcium and Magnesium levels in water to balance pH.

Post-Carbon Sediment Filter

Removes remaining fine and coarse particulate impurities/dirt and improves life of RO Membrane.

Post-RO Carbon Filter

Last level of purification acts like a polisher and enhances the taste of purified water.

Pre-RO Carbon Filter

Removes chlorine and organic impurities like harmful pesticides. It also adsorbs bad taste and odour-causing organic compounds from water.

Pre-Sediment filter

Pre-Sediment Filter for Heavy Sediment and Particulates (Dirt, Rust, Sand, Silt). It removes fine and coarse particulate impurities and improves life of the Carbon Filter.

RO Membrane

Unique RO technology membrane removes excess TDS, blocks dissolved impurities and chemical contaminants, while retaining essential minerals in the drinking water. It also helps removing dissolved salts, hardness, pesticides and heavy metals like arsenic, lead and mercury.

UV reactor

Acts as an additional stage of purification to further inactivate bacteria, virus and parasites to deliver safe water.


Toxic Metals/Materials

The Bureau of Indian Standards (BIS) has specified requirements for removal/reduction ofheavy metals in IS:16240. We tested the 10 brands for presence of the following heavy metals:

Arsenic: As many as six brands – Tata Swach, Zero B, Kent, Aquaguard, Electrolux and Usha – did not meet the requirement (a maximum 0.01 mg/l).

Copper: None of the brands met the requirement set by Indian Standard (0.05 mg/l).

Mercuy: All the brands more or less met the specified requirement – minor deviations were observed in Pureit, Aquaguard and Usha.

Cadmium: Minor deviation was observed in one brand, Pureit. All other brands met the standard requirement.

Iron: All the brands met the requirements, with the exception of deviation in two brands, Whirlpool and Usha.

Lead and chromium: All brands met the requirements.


Physicochemical Parameters

TDS

Total dissolved solids (TDS) refer to the combined content of all inorganic and organic substance contained in a liquid; these are present in a molecular, iodised, or micro-granular suspended form. RO systems are specifically designed to effectively remove TDS to a great extent. Where the TDS level of supply/ground water is high, from 1,000 up to 2,500–3,000, it is recommended that RO systems be installed for drinking-water purpose. A special cellulose membrane cartridge plays a key role in removing TDS from the input water.

As per Indian Standard, an RO system shall reduce TDS level of feed water to less than or equal to 500 mg/l.

  • Al brands reduced the TDS to below the limit specified (500 mg/l) when the input level was maintained at a fixed level.
  • Tata Swach scored highest on this parameter, followed by Aquaguard.
  • Some brands reduced the TDS level to below 100, which is also not desirable due to their reducing the intake level of essential minerals.

Turbidity Reduction

This refers to the amount of dissolved solid particles that are suspended in the water and that cause light rays shining through the water to scatter. Thus, turbidity makes the water cloudy or even opaque in extreme cases.

The turbidity of drinking water should not be more than 5 NTU and ideally be below 1 NTU. This is a key quality indicator for a water filter/purifier.

  • All the brands were able to remove turbidity to a level that makes it safe and suitable for drinking.
  • Kent, Whirlpool, LG and Tata Swach could remove 100 per cent turbidity and scored highest on this parameter.

Waste Water Score

As per Indian Standard, the minimum recovery of product water shall be equal to or more than 20 per cent. So, waste water should not be more than 80%.

  • Waste water was in the range of 62 per cent–71.4 per cent. This means the recovery of water in all brands was well above the prescribed limit of 20%.

RO and RO+UV water purifiers produce a lot of waste water during the purification process. Thus, if you pass four litres of water through an RO purifier, it will produce just about one litre of potable water. All the impurities are concentrated in the waste water and hence it is not drinkable.

Can the Waste Be Used?

a) First thing: test the TDS in the waste-water stream. If the TDS is below 1,000, you can use the water in your plants.

b) Alternately, mix some of that water with tap water to mop the house. Make sure you dilute it with tap water because if the TDS is high and you use just the RO waste to mop the floor, you may see some salt deposition after the water dries.

c) You can use the waste water to clean the sewage pipe at home or kitchen because of its saline nature..

d) You can use it to flush toilets.

Taste and Odour

Taste and odour of output water should be acceptable; in other words, there should not be any bad odour or taste.

All the brands gave output water with agreeable taste and odour.

pH Deviation

pH is a measure of the acidity or alkalinity of a solution. Aqueous solutions at 25 degrees C with a pH less than 7 are considered to be acidic, while those with a pH greater than 7 are considered to be basic (alkaline). When pH level is 7.0, it is defined as neutral at 25 degrees C.

As per Indian Standard, the pH of drinking water shall be 6.5 to 8.5.

Four brands – LG, Pureit, Zero B and Tata Swach – showed slight deviation from the pH requirement for drinking water.

Hardness Reduction

Water hardness denotes the presence of chloride and sulphates of calcium and magnesium salts in water. It is usually expressed in milligrams per litre of dissolved calcium and magnesium carbonate. Calcium and magnesium enter water mainly through the weathering of rocks. The more calcium and magnesium in water, the harder the water.

  • The lowest percentages of hardness reduction were found in Usha (96.88), Zero B (98.89) and Whirlpool (98.89).
  • All other brands reduced hardness by more than 99 per cent
  • Residual Chlorine

    The presence of residual chlorine in drinking water indicates that a sufficient amount of chlorine added initially to the water to inactivate bacteria and certain viruses that cause diarrhoea, as well as to ensure that the water is protected from recontamination. Residues of chlorine must be absent in the output water of water purifiers. This test was conducted after all other tests.

    • All the brands were able to reduce 100 per cent residual chlorine.


    Microbiological Activity

    The presence of bacteria and pathogenic (disease causing) organisms is a concern when considering the safety of drinking water. Pathogenic organisms can cause intestinal infections, dysentery, hepatitis, typhoid fever, cholera and other illnesses. As per the BIS requirement, the RO purifier shall inactivate/kill the selected standard challenging organism E. coli.

    E. coli %age Reduction Max Value

    When E. coli exceeds the permissible level in water, consumers are advised to boil the water they use for cooking and drinking, and even for brushing teeth. As per Indian Standard, the requirement is 99.9999 percentage reduction in E. coli. We observed all tested brands for four consecutive weeks to check percantage reduction in E. coli levels.

  • None of the brands we tested.met the requirements of Indian Standard for E. coli reduction. Hence, none of these RO water filters can be said to be completely safe for drinking.
  • E. coli %age Reduction Min Value

    When E. coli exceeds the permissible level in water, consumers are advised to boil the water they use for cooking and drinking, and even for brushing teeth. As per Indian Standard, the requirement is 99.9999 percentage reduction in E. coli. We observed all tested brands for four consecutive weeks to check percantage reduction in E. coli levels.

  • None of the brands we tested.met the requirements of Indian Standard for E. coli reduction. Hence, none of these RO water filters can be said to be completely safe for drinking.
  • MS2 Virus %age Reduction Max Value

    A microorganism smaller than bacteria, the MS2 virus cannot grow or reproduce apart from in a living cell. Viruses are the smallest agents of disease, and perhaps the most problematic, because they are as minute as 0.04 u (micron). Viruses cause many common human infections and are also responsible for a bevy of rare diseases. Viruses can infect all types of life forms, from animals and plants to bacteria and archaea.

    Based on the requirement specified by IS: 16240,MS2 virus was spiked in input water and the output sample was tested to check the virus-removal efficiency of purifiers.

    • None of the brands we tested met the requirement of Indian Standard for removal of MS2 virus. Hence, none of these RO water filters can be said to be completely safe for drinking.

    MS2 Virus %age Reduction Min Value

    A microorganism smaller than bacteria, the MS2 virus cannot grow or reproduce apart from in a living cell. Viruses are the smallest agents of disease, and perhaps the most problematic, because they are as minute as 0.04 u (micron). Viruses cause many common human infections and are also responsible for a bevy of rare diseases. Viruses can infect all types of life forms, from animals and plants to bacteria and archaea.

    Based on the requirement specified by IS: 16240,MS2 virus was spiked in input water and the output sample was tested to check the virus-removal efficiency of purifiers.

    • None of the brands we tested met the requirement of Indian Standard for removal of MS2 virus. Hence, none of these RO water filters can be said to be completely safe for drinking.

    Residual Pesticides

    • In India, high concentrations of both organochlorine and organophosphorous pesticides have been found in surface and ground water samples. Reverse-osmosis water filters are expected to remove pesticide residues.
    • We tested the 10 brands for pesticide residues. They were all able to reduce the pesticide residues and scored equally well.


    General Qualities

    Storage Capacity

    Water-storage capacity should be as declared by the manufacturer.

    • In five brands – Tata Swach, Electrolux, Usha, Aquaguard and Pureit – the water-storage capacity was found to be less than the declared.

    Convenience and Use

    All the brands scored equally well.

    Rate of Filtration

    It is the quantity of output water released from the system in a particular time period. Production rate should not be less than five litres per hour.

    Workmanship and Finish

    Overall, the workmanship and finish ranged from good to very good.

    Marking

    As per BIS requirement, a nameplate shall be fixed on the body of the RO system at a prominent location. The nameplate shall be marked with these details:

    • Name of manufacturer
    • Brand name
    • Production serial number
    • Model name or code
    • Production rate in l/h
    • Percent recovery of product water
    • Maximum operating TDS level
    • Supply voltage, whether single- or three-phase, frequency, volts and wattage

    The product should include these details as well: namely address of manufacturer, manufacturing date, MRP, and warning/precaution note. An instruction manual containing proper method of operation and use of the purifier shall be supplied along with the purifier. The purifier may also be marked with the Standard mark.

    All the brands had provided the required information

    Packaging

    As per the national standard, packing of RO purifier shall be sufficiently robust to give adequate protection from transportation damage. Being made from plastic material, the product has delicate assemblies and housing.

    • All the water purifiers were packed in thick, laminated paperboard carton supported by good-quality thermocol to give protection from damage.

    Instruction Manual

    A user’s manual for proper method of operation and use of the RO system shall be supplied along with the product. It shall also include details on the life and specification of all the filters/ consumables.

    • In the case of Aquaguard, no manual was provided with the unit.


    Manufacturers’ Comments

    Pureit - All Pureit devices comply with the US EPA norm for 6, 4, 3 log reduction for bacteria, virus and cyst. We have supporting test reports from reputed internationally accredited labs to support this. We propose the following steps: Please repeat the test done on fresh devices. a) Please test in triplicates and not just a single device. b) The model you have tested was a recommendation of June 2014. We have discontinued that product. We suggest you test Pureit Marvella RO+UV SKU. c) To avoid any contamination during set-up and installation, please get the same done by an authorised Pureit technician only. d) Get the tests done again in some other authorised and approved lab.

    Aquaguard Enhance RO - Our major concern is the test result for microbial performance.Our RO system can remove bacteria and virus effectively because of the mechanical separation. Membrane porosity is less than 0.0001 micron, which is much less than the bacteria and virus cell size (bacteria 0.2 micron and virus 0.01 micron). Also, it can separate the ionic-level chemicals, which are much smaller than bacteria and virus. We suggest that you check the microbial study again by means of proper chlorine tablet disinfection of the storage tank of the new unit.

    Aquaguard - Our major concern is the test result for microbial performance. Our RO system can remove bacteria and virus effectively because of the mechanical separation. Membrane porosity is less than 0.0001 micron, which is much less than the bacteria and virus cell size (bacteria 0.2 micron and virus 0.01 micron). Also, it can separate the ionic-level chemicals, which are much smaller than bacteria and virus. We suggest that you check the microbial study again by means of proper chlorine tablet disinfection of the storage tank of the new unit.

    Tata Swach a) Arsenic: Reduction observed as per the Consumer Voice test is be in range of 56 per cent–59 per cent. However, in the tests as per NSF certification and in our own tests, the membrane/unit has demonstrated more that 90 per cent reduction consistently. b) Copper: Reduction in first week is surprisingly low and then there is drastic improvement. c) Mercury and cadmium: Reduction results show a trend opposite to that for copper.

    Zero B - a) Total dissolved salts: The unit was tested at an inlet TDS level of 1,976 ppm. However, the limit for inlet TDS level for Zero B Wave purifier is 1,500 ppm. The same should be taken for testing the TDS reduction of the product (with reference to IS 16240: 2015). b) Hardness: The inlet water hardness level is 500 ppm for Zero B Wave. The unit was challenged for a hardness level of 2,000 ppm, which exceeds the inlet water limits by a big margin. c) Chlorine: The level of chlorine spiked in test water was 8.7 ppm, whereas the inlet chlorine level for the product is nil. It does not claim to remove any chlorine from the treated water. d) Toxic chemicals: We are surprised that Zero B Wave has not performed well for arsenic and copper removal from the water, though our in-house test results are satisfactory. e) Microbial reduction: We are surprised that the results are contrary to our in-house test results.

    VOICE Society’s specific reply

    The designated NABL lab has been regularly doing tests of drinking water and water purifiers as per relevant Indian Standards. In fact, some of the manufacturers have been sending samples from their production line for testing to this lab. So, the test procedure itself is well-known to them and cannot be questioned. VOICE Society has been conducting comparative testing of consumer products since 1991. The technical advisors of VOICE Society closely monitor the activities of laboratories during testing of products. Regarding the suggestion for retesting for E. coli, MS2 virus and heavy metals, it must be noted that the comparative testing of RO systems has already taken approximately five months. Further, the laboratory has confirmed that they have retested, on a random basis, 30 per cent of the RO systems available with them and found that the retest results are very close to the earlier results. Further, it is a time-bound project and retesting of new models of all the 10 brands is not feasible. Since this is an ongoing activity by VOICE, we will give due consideration to manufacturers’ suggestions in the next round of testing of water purifiers. As of now, their comments have been noted in our records and are reproduced in the report along with our findings.


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