Even in ‘pristine’ New Zealand, microscopic bacteria and viruses can be lurking in streams and hut water tanks. A water filter or purifier offers on-the-go peace of mind no matter where you drink from.
Water-borne hazards True, New Zealand backcountry streams are reasonably healthy but even so there is a small risk that water-borne illnesses like giardia, campylobacter, salmonella and E. coli can be picked up. The risk in urban environments increases after a disaster like an earthquake or when travelling to developing nations, where viruses and bacteria pervade waterways. Hut water should always be boiled or filtered/purified. Filters Filters are the first line of defence against larger-than-a-virus protozoa and cryptosporidia such as Giardia Lamblia and parvum. Filters remove sediment and organisms down to 0.4-0.1 microns. Purifiers Purifiers kill the much smaller viral and bacterial organisms. UV light is the most common and effective form of purification. It is important to follow instructions preciely to ensure the purification process is adequate. The full system Some systems use both a filter and purifier. The filter removes organisms down to 0.2 or 0.1 micron and the purifier deals with anything smaller. Unless the removal of organisms is at least 99.9%, there is a risk of infection. Flow rates The usual flow (or purification) rate is one to two litres per minute. It’s important to keep filters clean and free of sediment to ensure the flow rate remains high. Where to filter Always check – if possible – what’s in the water upstream to avoid contamination. Giardia slowly sinks, so draw your water where the flow is slow moving, away from the bank. Avoid muddy water as it can contain bacteria stirred up from the streambed and will also clog filters. Cleaning To ensure the long life of your filter, clean it regularly. This is usually done by rinsing and can be accomplished in the field as well as at home.










