There isn't a single best method, but there are 5 that adequately purify water according to Environmental Protection Agency (EPA) standards. These include 1) boiling for 1 minute if below 2000 m (6562 feet) and 3 minutes if above, 2) chlorine dioxide tablets, 3) MIOX purifier, 4) ultraviolet light (SteriPEN ), and 5) portable filtration with a absolute pore size <1 micrometer combined with halogenation or charcoal filtration (strength of recommendation [SOR ]: C, based on expert opinion and microbiological testing). Halogenation alone (ie, chlorine and iodine) is not effective against Cryptosporidium (SOR : C, based on microbiological testing)

Crawford, Paul

Nichols, William

Oldham, David

University of Missouri: MOspace

CliniCal InquIrIes From the Family Physicians Inquiries Network46	 vol 57, no 1 / january 2008  The Journal of family PracTice		What	is	the	best	portable		method	of	purifying	water		to	prevent	infectious	disease?Why boil water when there are  so many other options? These days, “boil it, peel it, or forget it” only goes so far with the unencumbered traveler. experience tells me that most hear “Boil it” and instantly go right to “Forget it!” Fortunately, there is an excellent resource to assist patients in choosing a personally acceptable portable water purification system. It’s called the Water Purification Database at usachppm.apgea.army.mil/WPD/CompareDevices.aspx.1 This outstanding database was developed by an impartial third-party for the us army and gives clear, well-organized guidance on over 60 purifiers. For each purifier, the guide covers efficacy against primary pathogens, purification mechanism, links to manufacturers, and an advantages/disadvantages breakdown (such as weight, cost, and ease of use). add this site to your Internet “favorites” folder. Timothy Mott, MD, FaaFPus naval Hospital, sigonella, Italyz	Evidence	summaryWith the rise in international travel and adventure sports, individuals are at in-creased risk of acquiring infections by drinking water from impure water sourc-es. Common waterborne infections that back-country and international travelers may contract include bacterial diarrhea, viruses, protozoa (such as Giardia and Cryptosporidium), and parasites (such as schistosoma). The risk of infection varies based on travel location. To prevent illness, travelers may seek medical guidance regarding safe water practice. In one study, 36% of travelers sought advice from a physician prior to international travel.2 Prevent-There isn’t a single best method, but there are 5 that adequately purify water according to environmental Protection agency (ePa) standards. These include 1) boiling for 1 minute if below 2000 m (6562 feet) and 3 minutes if above, 2) chlorine dioxide tablets, 3) MIoX purifier, 4) ultraviolet light (steriPen), and 5) portable filtration with a absolute pore size <1 micrometer combined with halogenation or charcoal filtration (strength of recommendation [sor]: c, based on expert opinion and microbiological testing). Halogenation alone (ie, chlorine and iodine) is not effective against Cryptosporidium (sor: c, based on microbiological testing). evidence-based answerclinical commentaryDavid Oldham, DO341st Medical Group,  Malmstrom Air Force Base, MontanaPaul Crawford, MDNellis Air Force Base  Family Medicine Residency,  Nellis Air Force Base, NevadaWilliam nichols, librarianEglin Air Force Base, Floridafast track5 methods meet EPA standards for lower pathogen counts under ideal conditions: y Boilingy  Chlorine dioxide tabletsy MIOX purifier y SteriPENy Filtration  vol 57, no 1 / january 2008 47www.jfponline.coming waterborne infections should be a component of traveler education, in ad-dition to other standard advice, such as mosquito avoidance and immuniza-tions.3 (For more on travel safety, see these Clinical Inquiries: “When should travelers begin malaria prophylaxis?” in the November 2007 Journal of Family Practice, pages 950–952, and “What is the most effective and safe malaria pro-phylaxis during pregnancy?” on page 51 of this issue.)Which	devices	meet	EPA	standards?The EPA has established a “minimal microbiological hazard” allowed for a Portable	water	purification:	How	do	these	6	methods	compare?	meThod effecTiveness advanTages disadvanTagesBoiling with cooling* Kills viruses, bacteria,   simple, universally accepted, Time-consuming, may require  protozoa, and parasites no special equipment required large amounts of fuelchlorine dioxide*  Kills bacteria, viruses,  same as chlorine/iodine Must wait up to 4 hours to treat  protozoa, and parasites treatment but also treats  Cryptosporidium, costs more than   Cryptosporidium, good  iodine/chlorine ($13 for 30 tabs)   palatabilitychlorine/iodine Kills bacteria, viruses, protozoa  Inexpensive, easy, lightweight,  Does not kill Cryptosporidium,  (not Cryptosporidium), and  treats large quantities poor taste, must wait for water to   parasites  be treated; contraindicated in     pregnancy, thyroid disease; not     recommended beyond few weeks     of usefiltration† removes parasites, Giardia,  able to use water immediately, Can potentially be expensive,  Cryptosporidium, and bacteria  removes sediment, many have  filters may clog easily, heavy, not   combination of activated carbon,  effective against small particle viruses,    chemical disinfectant, or both therefore should supplement with     chlorine or iodinemioX Purifier* Kills bacteria, viruses, light (8 oz), sturdy, treats large Cost $130, must wait for 4 hours  protozoa, and parasites quantities; requires camera  and treat with higher strength to treat   batteries and salt Cryptosporidium; requires 30 minutes    to treat viruses, bacteria, and Giardiauv light (steriPen)‡ Kills bacteria, viruses, protozoa,  light (8 oz), quick (treats 16 oz Cost $100, does not work in turbid  parasites in clear water of water in 1 minute) conditions      * Meets ePa standards.† some filtration systems meet ePa standards. see chppm-www.apgea.army.mil/WPD/CompareDevices.aspx for testing results  of individual filters.1‡ Meets ePa standards in clear water.Tablefast trackCliniCal InquIrIes48	 vol 57, no 1 / january 2008  The Journal of family PracTiceportable water purification system to be considered safe. Water purifiers must reduce bacteria by 99.9999%, viruses by 99.99%, and protozoa (such as Crypto-sporidium parvum) by 99.9% to receive an EPA certification number.4 There are no head-to-head trials com-paring the effectiveness of different meth-ods of purification to prevent infectious disease. The majority of the evidence is based on data provided by manufacturers to the EPA, with some independent studies and expert opinion (TAblE).Expert opinion recommends bring-ing water to a rapid boil for at least 3 minutes and letting it cool as an ef-fective means of water purification.5 Chlorine dioxide tablets, the MIOX pu-rifier, and UV light (SteriPEN) have all met EPA standards for lower pathogen counts under ideal conditions. Haloge-nation does not reduce Cryptosporidi-um below the microbiological hazard of 99.9%, but it is generally accepted to effectively treat viruses, bacteria, and other protozoa after filtering through a cloth to remove large particles.6 Filtration with an absolute pore size of <0.1 micrometer (10 times smaller than the EPA standard) has been gen-erally accepted as effective against protozoa and bacteria, but it is not effective against viruses because of their small size.7 When combined with either halogenation or charcoal filters, filtration can be effective against all pathogens.8Recommendations	from	othersThe US Army Center for Health Pro-motion and Preventive Medicine (USA-CHPPM) published a report in 2006 on the efficacy of commercial off-the-shelf individual water purifiers.8 Using Na-tional Sanitation Foundation Protocol P248 and applying it to “real-world” emergency military operational condi-tions, USACHPPM found that no device scored high on every attribute, and that overall scores for most devices were in the moderate range. The top score for any device was 79 (out of 100).8 The overall top 3 scoring products were: 1) the SweetWater Purifier from Mountain Safety Research; 2) the Micro-pur MP 1 tablets from Katadyn North America, Inc; and 3) the First Need Deluxe water purifier from General Ecol-ogy, Inc. nacknowledgmentsThe opinions and assertions contained herein are the private views of the authors and not to be construed as official, or as reflecting the views of the us air Force Medical service or the us air Force at large.references 1.  Commercially available individual water purifiers. Water Purification Database, us army Center for Health Promotion and Preventive Medicine Web site. available at: usachppm.apgea.army.mil/WPD/CompareDevices.aspx. accessed on December 7, 2007. 2.  Hamer DH, Connor Ba. Travel health knowledge, attitudes and practices among united states trav-elers. J Travel Med 2004; 11:23–26.  3.  Hill Dr, ericsson CD, Pearson rD, et al. The Prac-tice of Travel Medicine: Guidelines by the Infectious Diseases society of america. Clin Infect Dis 2006; 43:1499–1539.  4.  us environmental Protection agency: Guide stan-dard and Protocol for Testing Microbiological Wa-ter Purifiers: report to Task Force. Cincinnati, oH: us environmental Protection agency; 1987. 5.  Centers for Disease Control and Prevention. Water treatment methods. available at: wwwn.cdc.gov/travel/contentWaterTreatment.aspx. accessed on December 7, 2007. 6.  Gerba CP, johnson DC, Hasan Mn. efficacy of iodine water purification tablets against Crypto-sporidium oocysts and Giardia cysts. Wilderness Environ Med 1997; 8:96–100.  7.  Centers for Disease Control and Prevention, Divi-sion of Parasitic Diseases. Preventing Cryptospo-ridiosis: a guide to water filters and bottled water. available at: www.cdc.gov/ncidod/dpd/parasites/cryptosporidiosis/factsht_crypto_prevent_water.htm. accessed on December 7, 2007. 8.   Water supply Management Program Project no. 31-eC-03e0. Performance and health risk assess-ment of commercial-off-the-shelf individual water purifiers. aberdeen Proving Ground, Md: us army Center for Health Promotion and Preventive Medi-cine; 2006. available at: usachppm.apgea.army.mil/WPD/PDFDocs/Finalreport.pdf. accessed on December 7, 2007.The top 3  off-the-shelf  devices in US  Army tests were: y  SweetWater  Purifiery  Micropur MP 1 tabletsy  First Need  Deluxe purifier

What is the best portable method of purifying water to prevent infectious disease?

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