Consumer Voice - - Comparativ­e Test -

MS2 virus test | Mi­cro­bi­o­log­i­cal test (TPC) | Pes­ti­cide (lin­dane) | Heavy metal (ar­senic) |

Resid­ual chlo­rine

MS2 virus test

A virus is a small in­fec­tious agent that repli­cates only in­side the liv­ing cells of other or­gan­isms. Viruses can in­fect all types of life forms, from an­i­mals and plants to bac­te­ria. Based on the re­cent re­quire­ment of drink­ing wa­ter spec­i­fi­ca­tion (IS 10500), MS2 virus was con­sid­ered for test­ing and spiked in in­put wa­ter. The out­put sam­ple was then tested to check the virus re­moval ef­fi­ciency of the pu­ri­fiers. Most of the tested brands re­duced the per­cent­age of MS2 virus by more than 99 per cent. Brand Pure It re­moved it com­pletely. Uni­tex re­duced it by only 90 per cent, which is not de­sir­able in out­put drink­ing wa­ter of a pu­ri­fier.

Mi­cro­bi­o­log­i­cal test (TPC)

The pres­ence of bac­te­ria and path­o­genic (dis­ease­caus­ing) or­gan­isms is a con­cern when con­sid­er­ing the safety of drink­ing wa­ter. To­tal plate count (non­pathogenic) was checked to judge the ef­fi­ciency of the pu­ri­fiers in the out­put wa­ter. The main test to judge the mi­cro­bi­o­log­i­cal ef­fi­cacy was con­ducted in the en­durance test at de­fined/reg­u­lar in­ter­vals. Ex­cept for Pure It and Usha Brita, none of the brands com­pletely re­moved the mi­crobes from in­put wa­ter. How­ever, the level of TPC was in the range of 4–18, which is not high and is non­pathogenic.

Pes­ti­cide (lin­dane)

This test was con­ducted keep­ing in view the pes­ti­cides com­ing into var­i­ous potable wa­ter sources, viz. ground­wa­ter, rain­wa­ter, streams, etc. We had noted that some brands claimed to be ef­fec­tive in re­mov­ing pes­ti­cides. The pes­ti­cide lin­dane was added

in in­put wa­ter in 0.5 ppm con­cen­tra­tion. Out­put wa­ter was tested for the residues of added pes­ti­cide. Most of the brands re­moved the pes­ti­cide. Ba­jaj pu­ri­fier could re­move by 8 per cent only.

Heavy metal (ar­senic)

As per the na­tional stan­dard, toxic sub­stances like mer­cury, cad­mium, ar­senic, cyanide, lead, chromium and nickel should not be present in drink­ing wa­ter. Some of the brands tested also claimed re­moval of heavy metals. To ex­am­ine ef­fi­ciency in re­mov­ing heavy metals, we used ar­senic as in­put and tested the brands for its pres­ence in the out­put wa­ter. None of the brands of wa­ter pu­ri­fier was able to com­pletely re­move the heavy metal used for the test – that is, ar­senic.

Resid­ual chlo­rine

The pres­ence of chlo­rine residue in drink­ing wa­ter in­di­cates that a suf­fi­cient amount of chlo­rine was added ini­tially to the wa­ter to in­ac­ti­vate the bac­te­ria and some viruses that cause di­ar­rhoea, as well as to en­sure that the wa­ter was pro­tected from re­con­tam­i­na­tion. The residues of chlo­rine must be ab­sent in the out­put wa­ter of wa­ter pu­ri­fiers. Chlo­rine of 2 ppm con­cen­tra­tion was added in in­put wa­ter and out­put sam­ple was col­lected from the pu­ri­fier.

Chlo­rine was not de­tected in any of the brands. Chlo­rine is ac­tu­ally added in drink­ing wa­ter in or­der to dis­in­fect it and pre­vent the trans­mis­sion of wa­ter­borne dis­eases, but it can also be eas­ily per­ceived in the taste and smell of the wa­ter and its own dis­in­fec­tion by-prod­ucts are a mat­ter of con­cern.

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