FOR PHYSICOCHEMICAL PA­RAM­E­TERS

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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.

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