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January 2017 Issue
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2018’s best water filters and purifiers

Featured purifier: MSR Guardian Purifier ($699.99). Distributed by
A water filter or purifier offers peace of mind no matter the source of your water. 

Water-borne hazards

New Zealand backcountry streams are reasonably healthy. That said, there is still a risk that water-borne illnesses like giardia, campylobacter, salmonella and E. coli can be picked up. The risk closer to home increases after a disaster like an earthquake or when travelling to developing nations, where viruses and bacteria pervade waterways.


Filters are the first line of defence against larger-than-a-virus protozoa and cryptosporidia such as giardia lamblia and parvum. They remove sediment and organisms down to 0.4-0.1 microns.


Purifiers kill the much smaller viral and bacterial organisms. UV light is the most common and effective form of purification.

The full system

Some systems use both a filter and purifier. The filter removes large particles down to 0.2 or 0.1 micron and the purifier deals with anything smaller. Unless the removal or treatment of water 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 sediment will also clog filters.


Filters can be easily cleaned in the field, to ensure long life.

Now you know what to look for, it’s time to choose your filter or purifier…

SteriPEN Adventurer Opti $219.95
Compact handheld water purifier using ultraviolet light to kill up to 99.9999% of all waterborne bacteria and 99.99% of all viruses. Just insert batteries, push the ‘on’ button once and insert it into your water container. Uses two CR123A batteries. Purifier life 8000-litres Output 1-litre/90sec Weight 110g.

MSR Guardian Purifier $699.99
Squeeze-action purifier with hollow fibre filter to treat filthy water and remove viruses, bacteria, protozoa and particulate. Self-cleaning, impact resistant, withstands freezing. Flow rate 2.5-litre/min Cartridge life 10,000+litres Weight 490g.

SteriPEN Quantum RPS $199.95
Handheld water purifier uses ultraviolet light to kill up to 99.9999% of all waterborne bacteria and 99.99% of all viruses. Comes with RapidUV Reservoir to purify 4-litres/150sec and offers additional filtration and water storage for groups, outdoor recreation, or in emergency situations. Purifier life 3000-litres Output 1-litre/90sec Weight 335g.

MSR MiniWorks EX $229.99
Ceramic/carbon Marathon EX element removes bacteria, protozoa and unpleasant tastes and odours caused by organic compounds. Field maintainable, easy to clean. Flow rate 1-litre/min Cartridge life 2000+litres Weight 456g.

SteriPEN Classic 3 $169.95
Patented handheld water purifier uses ultraviolet light to kill up to 99.9999% of all waterborne bacteria and 99.99% of all viruses. Pre-filter included. Takes four AA batteries. Purifier life 8000-litres Output 1-litre/90sec Weight 225g. 

MSR TrailShot MicroFilter $129.99
Drink directly from the source or refill drink bottles, quick-deploy design, squeezing action pumps water through filter. Flow rate 1-litre+/min Cartridge life 2000-litres Weight 153g.