troclosene sodium or Silver ions for purification?

You can also go to a chemist and get a small bottle of "tincture of iodine" A couple of drops is about the same as 1 chlorine tablet although it does give water a slightly more metallic taste than the chlorine. Ive always relied on wise choice of water collection points and never got sick. When I was at school I did a fair bit of tramping in Fiordland. We never carried water If we wanted a drink pushing the hands into the moss on the side of the track which always had water running through it and waited for them to fill supplied all the water you needed with a nice earthy taste. Giardia is a horrible stomach illness although not especially dangerous.The following might help http://www.wrongdiagnosis.com/g/giardia/prevent.htm Avoid water that might be contaminated. 1. Avoid swallowing recreational water. Click here for information on recreational water illnesses . 2. Avoid drinking untreated water from shallow wells, lakes, rivers, springs, ponds, and streams. 3. Avoid drinking untreated water during community-wide outbreaks of disease caused by contaminated drinking water. In the United States, nationally distributed brands of bottled or canned carbonated soft drinks are safe to drink. Commercially packaged noncarbonated soft drinks and fruit juices that do not require refrigeration until after they are opened (those that are stored unrefrigerated on grocery shelves) also are safe. Click here to find out how to choose bottled water that is also safe to drink. 4. Avoid using ice or drinking untreated water when traveling in countries where the water supply might be unsafe. 5. If you are unable to avoid drinking or using water that might be contaminated, then treat the water yourself by: Heating the water to a rolling boil for at least 1 minute. OR Using a filter that has an absolute pore size of at least 1 micron or one that has been NSF rated for "cyst removal." Click here for information on choosing a water filter. If the methods above cannot be used, then try chemical inactivation of Giardia by chlorination or iodination. Chemical disinfection may be less effective than other methods because it is highly dependent on the temperature, pH, and cloudiness of the water. http://www.estes-park-information.com/giardia.html Prevention The best way to prevent giardia is to not drink untreated water. If swimming or playing in untreated water, try to avoid getting water in or around your mouth. Water from faucets in campgrounds is safe to drink unless otherwise labeled. If camping in the backcountry, you will need to treat your water with one of the following methods: Boiling Bring water to a complete rolling boil for at least five minutes. At sea level, you can get away with only one minute of boiling, but at high altitude, where water boils at a lower temperature, it's best to boil at least five minutes. Better safe than sorry. Filtration Use a filter that is 1 micron or less, or is rated for cyst removal by the NSF. Iodine or chlorine tablets use as directed. Iodine is probably more effective than chlorine and less nasty tasting, though it should not be used by anyone with a thyroid issue or who is pregnant. Iodine and chlorine are less effective than boiling or filtration. Also, don't add anything to the water (powdered lemonade, for example) until the chemical sterilization is complete. SteriPen This is a battery powered UV treatment device effective against giardia. Use as directed. Various brands of filtration devices built into straws, such as the "Life Straw," are not effective against giardia. If in doubt, boil or filter.

Hi, one bit of info that isn't too widely known: Filtering the water with ANY, even improvised, filtering device - as long as the filter itself is clean enough not to contribute to contamination itself - will significantly decrease your chances of getting sick. Why? Because the vast majority of germs is attached to particles in the water, and not free floating. Therefore, if you filter out the particles, you get rid of a large amount of the bad stuff as well. There was a study in India that found that the method used widely there - filtering through multiple layers of thin cotton fabrics - while seeming pretty useless, actually DOES help a lot, for that very reason. Of coruse, depending on water contamination and the capability of your immune system, filtering that way might not be enough, but it does help a lot. Cheers, Matt

...oh, and for the same reason, you should always filter at least with SOME filter (if just a coffee filter) before treating any water, because the much fewer remaining contaminants mean that there is a greatly increased chance of the chemical treatment actually working without any contaminants being left untreated. The same goes for UV-Treatment; less particles mean much better results. Matt

Rarely used any water treatments. Only time was a school trip doing the abel Tasman, during which most of the class got dehydrated due to not drinking enough water. A few of us did eventually drink untreated water which was good. Also collect water from slow or still water, never from rapids or flowing water. In still water the particles in the water have time to settle towards the bottom, compared with moving water where everything gets mixed up. But use common sense, a bubbly spring is probably safe to drink from. Also, only take water upstream from tracks and avoid stagnant looking water.

I always pick on free flowing but not turbulent water for this reason. Also deep enough that you collect well away from the bottom. Ive even filled 20 litre square bottles from the Wainagwa while camping there. The whole family drank that water.