PU­RI­FY­ING WA­TER: FIL­TRA­TION FACT & FIC­TION

NOW Magazine - Toronto Living - - Front Page -

Wa­ter fil­ters are de­vices that can im­prove the over­all taste, smell and ap­pear­ance of drink­ing wa­ter and can re­move some chem­i­cal sub­stances. Used mainly for drink­ing and cooking pur­poses, fil­ters are the most in­ex­pen­sive and eas­ily avail­able method of wa­ter pu­rifi­ca­tion. How­ever, pu­rifica- tion us­ing fil­ters is not 100 per cent. In gen­eral, wa­ter fil­ters re­move only the spe­cific types of sub­stances listed on their la­bels, like chlo­rine or lead. They do not re­move mi­cro-or­gan­isms and are in­tended for use with wa­ter that is known to be mi­cro­bi­o­log­i­cally safe. No sin­gle fil­ter can be used to re­move all types of sub­stances from wa­ter. LEAD FROM PIPES CAN LEACH INTO WA­TER There are many wa­ter fil­ter mod­els on the mar­ket. Each drink­ing wa­ter treat­ment sys­tem has its own ad­van­tages and dis­ad­van­tages. You must in­ves­ti­gate which unit or com­bi­na­tion of units is best suited for your house­hold. While mu­nic­i­pally treated wa­ter leaves the plant meet­ing all health and aes­thetic stan­dards, note that if your home has lead pipes or sol­der or if your wa­ter util­ity has lead pipes, you may have lead in your drink­ing wa­ter. If you aren’t sure and you live in an older neigh­bour­hood or older home, you can have your wa­ter tested for lead. If your wa­ter does con­tain lead, re­move wa­ter that’s sat in your pipes overnight by run­ning the cold wa­ter un­til it feels cold, or use a wa­ter fil­ter that’s been cer­ti­fied to re­move lead.

THREE PRIN­CI­PAL TYPES OF FIL­TERS

1. Par­ti­cle fil­ters op­er­ate on one ba­sic prin­ci­ple: they use a mem­brane to screen out or trap par­ti­cles based on their size. Th­ese fil­ters are rated ac­cord­ing to the pore size of the mem­brane, which is mea­sured in mi­crons – the lower the num­ber of mi­crons (i.e., the smaller the pore size), the more ef­fec­tive the fil­ter.

2. Ac­ti­vated car­bon (AC) fil­ters are most ef­fec­tive in re­mov­ing or­ganic con­tam­i­nants from wa­ter. Be­cause or­ganic chem­i­cals are of­ten re­spon­si­ble for taste, odour and colour prob­lems, ac­ti­vated car­bon fil­tra­tion can gen­er­ally be used to im­prove aes­thet­i­cally ob­jec­tion­able wa­ter.

3. Resin fil­ters con­sist of a mod­ule that con­tains resins able to re­move con­tam­i­nants such as lead and other heavy met­als, as well as min­er­als that cause de­posits in ket­tles and cof­fee mak­ers. Ba­sic wa­ter fil­ters can be found in hard­ware, depart­ment or gro­cery stores. Wa­ter equip­ment deal­ers sell some of the more so­phis­ti­cated ac­ti­vated car­bon fil­ters. Th­ese deal­ers are listed un­der Wa­ter or Wa­ter Com­pa­nies in the Yel­low Pages™. Wa­ter fil­ter sys­tems can be di­vided into two main groups: point-of-use de­vices and point-of-en­try de­vices. Point-of-use de­vices are usu­ally small units in­tended to treat wa­ter used for drink­ing and cooking. Th­ese can ei­ther be units in­stalled on sin­gle or mul­ti­ple taps or pitch­ers that fil­ter wa­ter poured in the top. Point-of-en­try de­vices are in­stalled on the main wa­ter sup­ply and treat all the wa­ter en­ter­ing the home. The prices of wa­ter fil­ters vary greatly, mostly depend­ing on the size of the fil­ter. Ac­ti­vated car­bon fil­ters range in cost from a few dol­lars to sev­eral hun­dred dol­lars. Faucet-mounted fil­ters usu­ally range in price from $20 to $60. Pitcher fil­ters are usu­ally the least ex­pen­sive, re­tail­ing for un­der $25. Will wa­ter fil­ters com­pletely clean and pu­rify your drink­ing wa­ter? Wa­ter fil­ters can­not mi­cro­bi­o­log­i­cally dis­in­fect drink­ing wa­ter. Wa­ter fil­ters can re­move cer­tain chem­i­cals and im­prove the taste, odour and ap­pear­ance of wa­ter.

CAU­TION: OLD FIL­TERS BE­COME TOXIC

One of the draw­backs of fil­ters is that if not used ac­cord­ing to the man­u­fac­turer’s spec­i­fi­ca­tions, they will al­low pre­vi­ously fil­tered con­tam­i­nants to be re­leased into the wa­ter. More­over, the buildup of or­ganic mat­ter on the fil­ter can pro­mote bac­te­rial growth in very short pe­ri­ods of time, even overnight. Stud­ies have shown that lev­els of bac­te­ria present in wa­ter that has passed through an im­prop­erly main­tained home fil­tra­tion de­vice may be up to 2,000 times higher than lev­els in un­fil­tered wa­ter.

WANT MORE IN­FOR­MA­TION?

More in­for­ma­tion about wa­ter fil­ters can be found at Health Canada’s web site, www.hc-sc.gc.ca/waterqual­ity, which de­scribes many ac­tiv­i­ties re­lated to drink­ing wa­ter qual­ity. You can also check the web site of NSF In­ter­na­tional, www.nsf.org, for in­for­ma­tion about health-based per­for­mance stan­dards re­lated to drink­ing wa­ter treat­ment units. The NSF also pro­vides a list­ing of sys­tems that it has cer­ti­fied at www.nsf.com. The Canadian Wa­ter Qual­ity As­so­ci­a­tion site, www.cwqa.com, is also an in­dus­try source of in­for­ma­tion for drink­ing wa­ter treat­ment units. Your lo­cal wa­ter util­ity may also be of as­sis­tance.

This ar­ti­cle was sup­plied by CMHC (the Canada Mort­gage & Hous­ing Cor­po­ra­tion). Go to www.cmhc-schl.gc.ca for other ar­ti­cles.

FIL­TERS RE­LEASE THEIR TOX­INS INTO THE WA­TER IF NOT CHANGED REG­U­LARLY.

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