Cheap and light filtration?`

Hello. It's possibly a reflection of where I visit, but I usually don't bother. I keep some tablets in my first aid kit just in case, but haven't touched them for a couple of years. There are some exceptions (like water that's run through a farm or if I have reason to believe there's something yucky in the area), but generally if it's coming straight out of the mountains I tend to trust it.

The paper to read on Giadia is http://www.ridgenet.net/~rockwell/Giardia.pdf and I think we can transfer Dr Rockwell's finding to the NZ situation as well. What it comes down to is that while there is Giardia out there, the concentrations are so low that you are unlikely to get Giardia from backcountry water. The problem for public health people is that because back country water is not treated they can't gaurantee it is safe. This has been used by the people who sell filters to market their product. It is a con, just like bottled water. The trick is to "drink smart". ie just give a bit of thought what is upstream before you drink. My experiece is that generally backcontry water is safe to drink and DOC Hut supplies are OK too. I had Giardia once, caught in Burma, not tramping. It is a easily treated but boy! is it also a good way to loose some weight.

Interesting, thanks. I've been happy to drink the water from streams and rivers until I got to a south Marlborough one last week. It was tepid and had some algae growth just about all the way up. I hadn't brought any water - I assumed that this off-the-beaten-track stream would be fine. In for a penny... I didn't get sick at all, but also noted several carcasses lying near the stream at the bottom of slips (3 goats, 2 deer, 1 possum). One of them was fresh enough to be smelly for some distance. Unfortunately, I had already sampled the downstream water. Oh well, still didn't get sick - but it made me think :)

I stood and listened as a Salesperson at bivouac expounded on the virtues of a filtration system without actually saying you need it in Newzealand. I could see the conflict in the customers face as he was having trouble balancing fact with fiction but enough doubt existed to swing the sale. I say i stayed to listen as this question has always intrigued me. Common sense has always prevaled. Out of a still pool cook it. Fast moving back country streams where chemicals havnt been used recently no problem. As you get closer to civilization carry your own. The odd dead animal while raising the odd concern havent killed or made me sick but again I have usually only drunk from fast moving water i figure the parts per thousand equation make my chances greater. (i bet some of you can make mincemeat out of that theory).

I always take my water to drink from pools and rarely from the moving or rapid sections of rivers. I beleive that in pools most of the flotants would sink and settle near the bottom, so by taking water near the surface it should be fairly pure. In rapids I imainge the water being all mixed. I have drunk from a lot of rivers over the years and never gotten sick. A few are even on the council watch less for cotaiminations (mainly dairy run off). Probably not the best to drink from buy I am fine. I only drink from them during periods of low flows when surface run off is low and most of the water is from springs.

Pmcke has provided a clear and perhaps accurate perspective. Be aware of the source. Take it from a side stream before the main river option. Flowing water is generally more reliable. I've never bothered with a filter or treatment in NZ.There are so many water sources. I've seen some unscrupulous people throw excess food eg rice on the rooves of huts to dispose of it and that subsequently enters the water supply. Therefore i'd be more concerned about water from popular huts on great walks than a waterway nearby. Unfortunately, i've also seen foreign backpackers walk away from a waterway after toileting, unaware of the danger they pose. I do use a treatment process in Aust. however. Water there is far less accessible and reliable. Having used all types of filters and treatments and understanding their pros and cons due to working in retailing them for some years, i now have a Steripen (UV light treatment) and it is very convenient. It's not cheap though. Cheap and light doesn't necessarily mean the best result. Do your research.

You should read Lofty Wiseman's "SAS Survival Guide" for some great ideas on how to find, filter and manage water. If you have time on your hands like when camping then you should try out a solar still or just boil any water you find even if it's from a stream. There is even an iPhone application that you can get if you are not into reading books -- www.sassurvivalguide.com

John Aitken, a Chch microbiologist, did a couple of different surveys of water in Arthurs Pass for Giardia and E.Coli and other greeblies. The only place he found Giardia was in Twin Creek which he suspects is connected to the toilets at the Temple Basin Skifield via an earthquake fault line. He sampled the Hawdon River and all the way down to the mouth of the Waimakariri River. Water was very clean from upstream of the old hut site. This was while the hut was still in use before it was burnt down. The water from the tank was inferior due to bird poop being deposited on the roof but still reasonable. As the samples were taken from further down the Hawdon, their quality deteriorated but they were still quite acceptable. However I wouldn't be swimming in the Waimak as it got downstream of dirty dairying, judging from his results which are quite old. Of course it's incredibly deteriorated since then. The nasty Giardia variety in the NZ National Park environment will die out in 18 months as there are no hosts. Deer and other critters do host other giardias but they aren't the bad guy (giardia intestinalis - was g.lamblia). These nasties survive in the US and other places because they have hosts such as beavers. Giardia is sometimes known as beaver fever. However I don't have much info on cryptosporidium! I pretty much practise what the above contributors do e.g. take my water from the top layer of tarns if I have to at the head of them. I avoid tarns on touristy routes e.g. Tarn Col between the Otehake and the Edwards. I believe European hikers don't bury their poop which may work for continental summers where the sun sterilizes it but it's not a good idea here.

yea ive done quite a few tramps and have never filtered any water.... and what a suprise ive never been sick. i feel that as long as it looks clean it is safe to drink and if its fast moving even better....