Water purifier- which one to buy?

@Berend de Boer "Finally I would say you probably can drink water in NZ streams safely, if you don't drink too much. You have one giardia per 20 litres here, and you need to get about 5 to get sick, so about 100 litres. This seems to suggest to me that for one or two days drinking from a stream is fine, for a couple of days you probably want to filter. " I'm sorry, but I'm pretty sure that's not how science works.

Very few streams in n.z. mountains have Giardia. I've never treated any water in decades. Never had gut problems... Abel tas I would treat the water from any stream.

I tramp in the lower north island. Tararua and ruahine. But have tramped all over north island. I have never treated water and never been sick. Most tramps start in farm land but I start with a full bottle of water. But once away from the farms it's all good. I've got water from pretty stagnant tarns and not been harmed. Common sense is an interesting quality. Some have it and some don't. Those who ask a lot of questions sometimes don't have it. But if you use it you will usually be fine. Don't drink downstream of man. Ie farmland etc. in the real bush it's all good. Unless you read otherwise. I don't treat hut tank water either and I've never had a crook gut. I have a stiripen that I use on overseas tramps. But when I tramp in NZ it stays in my wardrobe. If your worried just get a water purifier that is reputable and you can afford.

But wait! Nobody's yet mentioned DoC's ubiquitous warning signs describing how the water at all of its facilities is only probably completely and absolutely fine, and that people could consider boiling or treating the water just in case. Surely those warnings factor into people's consideration of the risks!

surely those warnings are a get out of jail free card for DOC if anyone complains they got sick if the water quality changes, all the rangers say the same thing, none of them have ever gotten sick in years or decades...

Occasionally there is an outbreak of illness e.g. at Blue Lake Hut last year, caused by dead critters in the water tank. The Te Araroa people were communicating this to each other and eventually it got sorted by flushing the tank. Other than that, I agree with the folks here that it's generally only a problem on the tracks popular with the overseas tourists such as AT and the Routeburn. I have often quoted on this website John Aitken, the former section head of microbiology at SCL, who told us when invited to talk at our tramping club on water quality that the only giardia he found in the entire Arthurs Pass National Park was located in Twin Creek which is in the catchment for Temple Basin Ski Field. Here's a link to information about John and his current research: http://www.stuff.co.nz/national/health/80201367/Christchurch-microbiologist-may-have-cracked-Crohns-disease Giardia lamblia, which is the pathogenic form causing diarrhoea, is unable to survive beyond 18 months in the NZ environment as we don't have suitable hosts such as beavers. Of course if people carrying it come here and do their number 2's uphill of where we get our water from then we can contract it. Our introduced animals in the backcountry can host giardia but it's not the harmful form. John found there was a bit of e.coli from tank water deposited by bird feces from the roof but it wasn't a health issue. I can't remember what he had to say about campylobacter but suspect it might be of a similar incidence to giardia.

I've had giardia. From Fiji. It truly sucked! You don't want it!!

Just ordered a Sawyer. Think, this was a good choice. Also ordered a Jetboil Flash Lite cooker system, as my current cooker is not really good for tramping. I have the Campingaz Bleuet 206, which works with the 206D gas tanks. The tank has to stay connected to the burner unit, until it is empty. Not easy to find a good place in your backpack for this thing. Another downside is, that the pot sits on 3 tiny metal rods, it falls off quite easily. The Jetboil seems to be a better option for tramping.

Don't forget to post a gear review in a year or so :-)

Not a filter, but does anyone have any experience of those UV light producing sterilizing thingimies?