Water Treatment Systems
Abstract & Commentary
Synopsis: Portable water treatment systems for travelers vary greatly. The efficacy of a system depends on its mechanism of treatment as well as its specific design. The hand-pump filters tested are in general the most reliable and efficacious in removing bacteria.
Source: Schlosser O, et al. Bacterial removal from inexpensive portable water treatment systems for travelers. J Travel Med. 2001;8:12-18.
Efficacies of portable water treatment systems available on the French market under $140 were studied. These systems included 4 chemical agents, 2 iodine resin purifiers, and 4 filters.
The chemical agents tested included 3 chlorine compounds (Drinkwell chlorineâ, Aquatabsâ, and Hydroclonazoneâ), and 2% iodine in ethanol. The iodine resin purifiers tested were the PentaPureâ straw Outdoor M1-Eä and the PentaPureâ Traveler (which is attached to the faucet). The filters tested included Pres2Pureâ (a flexible bottle), and 3 hand-pumps (Mini Ceramicâ, First Needâ Deluxe, and WalkAboutâ).
The water in the study came from the river Marne, near Paris. Both raw river water (turbid water) and sand-filtered water from a water treatment plant (clear water) were used. Bacterial contents of the water samples were measured before and after treatment using 3 methods: conventional culturing techniques, Colilertâ/Quantitray method, and fluorescent count of viable but not culturable bacteria.
Testing showed that sand-filtered water was clear but contained a significant number of coliforms including Escherichia coli. Tests on clear water showed that Hydroclonazoneâ and Pres2Pureâ bottle were ineffective. Thus, these 2 systems were not tested further with turbid water. The Mini Ceramicâ performed well, followed by the First Needâ Deluxe. The WalkAboutâ filter removed bacteria well in the first test, but the system became contaminated. The rest of the systems performed poorly.
Tests on turbid water showed that the hand pump filters were all effective in decreasing the turbidity of the water, with Mini Ceramicâ leading in performance followed by the WalkAboutâ and then the First Needâ Deluxe. Furthermore, the 3 hand pumps effectively removed coliforms including E coli, with the exception of the WalkAboutâ on 1 sample, when 2 coliforms/100 mL in the effluent were cultured (from a sample that contained 57,000 total coliforms/100 mL). Enterococci was identified in the effluent after treatment with Aquatabsâ and the straw Outdoor M1-Eä. Similarly, the chemical agents and the PentaPureâ straw Outdoor M1-Eä were ineffective in inactivating coliforms.
Comment by Lin H. Chen, MD
The most reliable method of making water safe for drinking is to boil it. This is not feasible for many travelers. Therefore, some travelers rely on purchasing bottled water. Yet other travelers may be going to areas where the availability and reliability of bottled water are uncertain, and portable water treatment systems become crucial. Travel medicine consultants may be asked to recommend a water treatment system, but there is little scientific literature comparing the numerous systems.
NSF International is a company that tests and certifies water filters for removal of protozoa.1 A list of filters that have passed NSF tests is available (1-800-673-8010; NSF, 3475 Plymouth Road, P.O. Box 130140, Ann Arbor, MI 48113-0140). However, the filters are not certified for their ability in removing bacteria or viruses.
In a prior study, Ongerth and associates had evaluated water treatment systems at removing Giardia lamblia for the backcountry traveler.3 None of the chemical treatments and none of the contact disinfection devices provided sufficient cyst inactivation. Cysts were inactivated by heating to 70°C for 10 minutes, and cysts were effectively removed by some (but not all) of the filters tested. The First Needâ Water Purification Device and the Katadyn Pocket Filterâ were shown to be effective.
In evaluating drinking water for public health protection, E coli is felt to be the best biological indicator.2 The Schlosser study investigates the removal of bacteria by portable water treatment systems, and complements the Ongerth study on G lamblia. This information is sorely needed to make specific recommendations for travelers. The conclusions are straightforward and comparable to the study on G lamblia cysts: the chemical systems and iodine resins are ineffective or unimpressive; the hand-pump filters in general are the most reliable in removing bacteria.
Each water treatment system has inherent problems or inconveniences. The chemical systems may impart an unpleasant taste. The iodine resins may lead to thyroid abnormalities.4,5 The hand-pump filters may be bulky. Given their performance in removing bacteria, the hand-pump filters are easily the preferred portable water treatment systems. The Mini Ceramicâ, manufactured by Katadyn Produkt AG, the First Needâ Deluxe, manufactured by General Ecology, Inc., and the WalkAboutâ, manufactured by SweetWater, should all be available in the US market. Additional studies that evaluate bacterial removal by the other portable water treatment systems available in the United States would be welcomed.
1. CDC. Treatment of water. In: Heath Hints for the International Traveler 1999-2000. Atlanta, Ga: DHHS. 163-165.
2. Edberg SC, et al. Escherichia coli: The best biological drinking water indicator for health protection. J Appl Microbiol. 2000;88 Suppl:106s-116s.
3. Ongerth JE, et al. Backcountry water treatment to prevent giardiasis. Am J Public Health. 1989;79(12): 1633-1637.
4. Liel Y, Alkan M. Travelers’ thyrotoxicosis. Arch Intern Med. 1996;156:807-810.
5. Khan LK, et al. Thyroid abnormalities related to iodine excess from water purification units. Lancet. 1998; 352:1519.