FOR PHYSICOCHEMICAL PARAMETERS

Undesirable Substances | Toxic/Heavy Metals | Pesticide Residues | TDS | pH | Turbidity | Colour

Undesirable Substances

Apart from the toxic metals and substances, there are a few undesirable substances that can make drinking water unhealthy/unhygienic or hamper its taste. All these undesirable substances were tested as per the requirements of IS, and a handful of brands contained some of these in negligible quantities.

• All brands were found to be within the limits set by Indian Standard for these substances: aluminium, anionic surface-active agents, antimony, barium, borates, copper, iron, manganese, mineral oil, nitrite, phenolic compounds, residual chlorine, selenium and sulphide.

Nitrate is a colourless, odourless and tasteless compound that is present in some groundwater. High nitrate levels in water can cause methemoglobinemia or blue baby syndrome, a condition found especially in infants less than six months old. The stomach acid of an infant is not as strong as in older children and adults. This causes an increase in bacteria that can readily convert nitrate into nitrite (NO2).

Nitrate (as NO3): Nitrate in drinking water can be a maximum of 45 mg/litre. All five brands contained some amount of nitrate, but it was well within the maximum permissible limit.

Fluoride (as F): As per the national standard, the maximum amount of fluoride permissible in packaged drinking water is 1 mg/litre. All brands were found to be within the permissible limit.

Children aged eight years and younger exposed to excessive amounts of fluoride have an increased chance of developing pits in the tooth enamel, along with a range of cosmetic effects on teeth.

Silver (as Ag): Levels of silver up to 0.1 mg/litre can be tolerated without risk to health. Silver was not detected in any of the tested brands.

Chloride (as Cl): The maximum permissible limit for chloride is 200 mg/litre. Chloride was well below the maximum permissible limit in all tested brands.

Chloride in drinking water is generally not harmful to people until high concentrations are reached, although chloride may be injurious to some people suffering from diseases of the heart or kidneys. Restrictions on chloride concentrations in drinking water are generally based on taste requirements rather than on health. Liquid chlorine is mixed into drinking water to destroy bacteria.

Sulphate (as SO4): The permissible limit for sulphate is 200 mg/litre. It was not detected in Aquafina, while in the others it was well below the maximum permissible limit.

Sulphate is a naturally occurring substance that contains sulphur and oxygen. Sulphate is generally considered to be non-toxic. However, the consumption of drinking water containing high amounts of sulphate may result in intestinal discomfort, diarrhoea and consequently dehydration.

Alkalinity (as HCO3): Alkalinity is not considered to be detrimental to humans, but is generally associated with hardness, high pH values and excessive dissolved solids, all of which may be undesirable. HCO3 should not exceed 200 mg per litre. All the brands were found well below the permissible limit for alkalinity

Calcium (as Ca) and Magnesium (as Mg): Calcium in water and certain other minerals in water are healthy. Calcium-rich water has a higher pH and that is better than drinking acidic water. However, calcium and magnesium are components of permanent hardness, and thus are undesirable in drinking water. The amount of calcium should not exceed 75 mg per litre, while magnesium should not be more than 30 mg per litre. In the tests, all brands were found to contain very slight amounts of calcium and magnesium

Sodium (as Na): Sodium is an essential mineral in our diet. It is commonly found in the form of sodium chloride (salt). Salt has no smell and it dissolves easily in water and gives water a salty taste at high levels. The amount of sodium should not exceed 200 mg per litre. All the brands were found well within the maximum permissible limit for sodium.

Toxic/Heavy Metals

As per the national standard, the toxic substances that should not be present in drinking water are mercury, cadmium, arsenic, cyanide, lead, chromium and nickel.

All the brands were tested for the presence of toxic substances and heavy metals. These were detected in a marginal amount in DJB water but were well below the permissible limit. The rest of the brands were clear.

Pesticide Residues

Pesticide is a chemical or biological agent (such as a virus, bacterium, antimicrobial, or disinfectant) that deters, incapacitates, kills, or otherwise discourages pests. Pesticides may cause acute and delayed health effects in people who are exposed. Such adverse health effects range from simple irritation of the skin and eyes to more severe effects like affecting the nervous system, mimicking hormones causing reproductive problems, and causing cancer.

As per Indian Standard, the maximum permissible limit is 0.0001 mg/litre for individual pesticide and 0.0005 mg/litre for total pesticide residues. All tested brands were within the requirement set by the national standard. Traces of 2,4dichlorophenoxyacetic acid were found in Aquafina but these were well below the specified limit.

Total Dissolved Solids (TDS)

Total dissolved solids are the amount of minerals, salts or metals dissolved in a given volume of water. TDS is directly related to the purity of potable water and the quality of water purification systems, and affects everything that consumes, lives in, or uses water, whether organic or inorganic. The standard/ regular practice of packaged drinking water in

industry is to take the potable water from a regular source and demineralise the water through the RO system and in the required quantity to balance the TDS level as permitted in the national standard.

As per Indian Standard, total dissolved solids in packaged drinking water shall be a maximum 500 mg/ litre.

• TDS in all brands was lower than the maximum permissible limit.

• Highest TDS was observed in Bisleri (98 mg/ litre), followed by DJB Jal (95 mg/litre) . TDS was lowest in Kinley (27 mg/litre).

Water is a good solvent and picks up impurities easily. As per WHO guidelines for drinking water quality, water with extremely low concentrations of TDS may be unacceptable to consumers because of its flat, insipid taste. At the same time, drinking water becomes significantly and increasingly unpalatable at TDS levels greater than about 1,000 mg/litre.

pH

The pH level of your drinking water reflects how acidic it is. pH stands for ‘potential hydrogen’, referring to the amount of hydrogen mixed with the water. pH is measured on a scale that runs from 0 to 14. A measurement of seven is neutral, indicating there is no acid or alkalinity. A measurement below 7 indicates presence of acid and a measurement above 7 indicates alkalinity. The normal range for pH in packaged drinking water as per Indian Standard is between 6.5 and 8.5.

All the brands of packaged drinking water were within the specified range for pH.

Turbidity

Turbidity is a principal physical characteristic of water. It is caused by suspended matter or impurities that interfere with the clarity of the water. These impurities may include clay, silt, finely divided inorganic and organic matter, and soluble coloured organic compounds.

Turbidity in water shall not be more than 2 nephelometric turbidity units (NTU).

Turbidity was less than the maximum permissible limit in any of the brands.

Colour (in hazen unit) was not detected in any of the brands.