Filters and purifiers ensure the water you drink will be safe, no matter how filthy the source.
Save time and lighten your load
Filters and purifiers can reduce pack weight by allowing water to be sourced on the go, rather than carrying extra litres (1l weighs 1kg) from home. These units also save time as water needn’t be boiled to make it safe to drink.
Water-borne hazards
Water filters and purifiers are designed to provide protection from water-borne illnesses like giardia, campylobacter, salmonella and E. coli.
When to use
If you’re carrying a filter or purifier, it should be used every time water is collected for drinking, even in the backcountry where the risk of contracting a water-borne illness might be small. The risk increases in more popular areas, where people might go to the toilet near waterways or where animals are grazed. In urban environments, a disaster like an earthquake can turn a water filter or purifier into a life-saver.
Because bird droppings and animals often end up in hut water tanks, it’s wise to treat (or at least boil) all drinking water.
How 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.
What filters do
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.
What purifiers do
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 precisely 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.
Cleaning
To ensure the long life of a filter, clean it regularly. This is usually done by rinsing and can be accomplished in the field as well as at home.
Platypus QuickDraw Microfilter with 1l bottle $129.99
Simply fill and squeeze for safe and instant hydration. RF-welded taste-free reservoir has a wide mouth for rapid filling at any water source, 0.2 micron hollow fibre cartridge removes 99.9999% of bacteria and 99.9% of protozoa. Flow rate Up to 3-litre/min Cartridge life 1000-litres Weight 101g. www.ampro.co.nz
Aquatabs $14.99
These purification tablets kill waterborne organisms such as Giardia that cause stomach upsets, easily making water safer for drinking, brushing teeth and food prep. www.ampro.co.nz
Steripen Classic 3 $249.95
A versatile, simple-to-use UV water purifier that kills up to 99.9999% of all water-borne bacteria and up to 99.99% of all viruses. It has an LED indicator panel, comes with a pre-filter to remove larger particulates and requires 4xAA batteries. Purifier life 8000-litres Output 1-litre/90sec Weight 225g. www.outfitters.net.nz
Steripen Adventurer Opti $299.95
Designed for use where there’s no access to power for several days, this rugged unit uses ultraviolet light to kill up to 99.9999% of all waterborne bacteria and 99.99% of all viruses. Single-button operation and runs on two CR123A batteries. Purifier life 8000-litres Output 1-litre/90sec Weight 110g. www.outfitters.net.nz
MSR TrailShot MicroFilter $169.99
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. www.ampro.co.nz
Lifesaver Wayfarer $259.99
This pump-style water purifier removes bacteria, viruses and protozoa. Replaceable activated carbon disc reduces chemicals and heavy metals. Includes spare filter cartridge and 3x activated carbon discs. Purifier life 5000l Output 1.4-litre/min Weight 290g. www.plg.com.au
MSR MiniWorks EX $299.99
Easy-to-maintain microfilter that removes bacteria, protozoa and unpleasant tastes and odours caused by organic compounds. Field maintainable. Flow rate 1-litre/min Cartridge life 2000+litres Weight 456g. www.ampro.co.nz
MSR Guardian Purifier $999.99
The Guardian offers long-lasting performance with self-cleaning ease and provides full viral protection when traveling in developing nations and popular wilderness areas. Advanced hollow fibre filter offers reliable purification of even filthy water conditions. Flow rate 2.5-litre/min Cartridge life 10,000+litres Weight 490g. www.ampro.co.nz
