AO Smith AO Smith X4 (Passion Red) Water Purifier
Purity through 5 stage purification, Advanced unique patented SSM technology, Advanced Pre-filter and sediment filter, Asthetics, Conveience
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A. O. Smith X4 is a 100% RO water purifier with 2 year warranty on the RO membrane. It incorporates a 5 stage purification system, along with Side Stream RO Membrane Technology.

If you need futher guidance regarding various things to consider while purchasing Water Purifier, please read our Conzumr Guide

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Installation Counter-Top

RO: Reverse Osmosis

Storage Yes
Tank Capacity 9 L
Electric Non-Electric
Total Score out of 100 71
MRP (Rs) 16750
Manufactured/Marketed by A.O Smith India Water Products Pvt. Ltd
Purification Capacity Per Hour 15 Ltr/hr
Power Consumption 48 W
Available on Conzumr Since August 2020

Installation Counter-Top
Purification Type RO

RO: Reverse Osmosis

Storage Yes
Tank Capacity 9 L
Number of Purification Stages 5
Electric Non-Electric
Colour Passion Red
Material of Body Plastic parts
Brands Tested
Total Score out of 100 71
MRP (Rs) 16750
Manufactured/Marketed by A.O Smith India Water Products Pvt. Ltd
Purification Capacity Per Hour 15 Ltr/hr
Filter Cartridges Post-RO Carbon Filter, Pre-Filter, Pre-RO Carbon Filter

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.

TDS Reduction ≥95 approx
% Water Recovery 30
Weight and Dimensions
Net Weight 8.8 kg
Width 314 mm
Depth 325 mm
Height 503 mm
Input Voltage 150 – 300 VAC/ 50 Hz
Power Consumption 48 W
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.

Score out of 14 (for all toxic metals) 12.48
Physicochemical Parameters
TDS 3.91

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 3.84

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 3.28

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 4

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 2.75

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 2.97

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 2

    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 99.9

    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 Score out of 16 4.44
    MS2 Virus %age Reduction Max Value 99.5 cfu/100ml

    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 Score out of 16 4.2
    Residual Pesticides Able to reduce the pesticide residues

    • 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 4

    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 5

    All the brands scored equally well.

    Rate of Filtration 2.4

    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 3.8

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

    Marking 3

    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 2

    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 2

    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.