Water Puri systems: Microns 0.002 filter Help please?

[little_leaf177]

Hell0000,
I'm hoping there's one or two chemistry boffins out there who can help explain a thing or two to me please..
When it comes to filter systems they all describe their filter as giving the purest water available... which is true when you compare it to the bacteria ridden water you could be drinking from the stream...
But what im intrigued to know is how these microns work..
I.e If pollen is 100 Microns, spores are 10 microns, bacteria is 1.0 micron and virus's are 0.01 Micron

How can a filter take out "virus's and bacteria" if their filters are sized as the following
- "0.1 absolute micron biological filtration" (sawyer Squeeze)

or

the 2 micron bacteriostatic pores of the Aqua-pure traveller ...

I've used the aquapure traveller recently and although I should have done my research prior to the trip about this I didn't.. by like stated earlier I am intrigued. So I ended up using iodine aswel as a 'just in case'..

So if anyone can help explain these process's how 0.1 micron & 2micron filters can remove virus's from water that are supposedly 0.02microns... it baffles me so a simple answer other than 'magic' would be extremely helpful PLEASSSEEEE

Cheers
Leaf177

 

[rg598]

It doesn't. Those filters do not claim to remove viruses, only bacteria, sediment and protozoa (the Sawyer Squeeze Filter-0.1 microns). The Aqua Mira filter with 1.0 pore size does not filter all bacteria either. If you want to treat for viruses you need a chemical component. I'm not sure where you saw the claims that these filters remove viruses.

 

[petrochemicals]

remove = kill

 

[little_leaf177]

In references to virus's....

aquapure - http://www.purehydration.com/aquapure-traveller/#.UsH92pEgGSM
I'll hand it to you on that, the sandard sawyer doesnt say it takes out virus's... But im sure ive seen it (if not my brain is at fault here)
however the pointzerotwo does (0.02 micron filter)

" A4.2: Sawyer PointZEROTWO™ Purifier - If viruses are an issue, we offer the PointZeroTWO™ Purifier (0.02 micron absolute pores), the first and thus far only portable purification device to physically remove viruses which it does at a >5.5 log (99.9997%) rate, exceeding EPA and NSF recommendations. Due to the significantly higher level of filtration, PointZEROTWO's flow rate is considerably slower than the PointONE™ filters."

 

[Andy BB]

THe Pure systems do claim to remove viruses and heavy metals, despite having a 2 micron filter. Seems they have technology "Mechanically Advanced Disinfection" as well as activated charcoal filters. Disadvantage seems to be amount of water a cartridge can treat - 350litres or less, depending on quality of water. - at which stage it deliberately stops allowing water to flow and you need to fit a new cartridge. Presumably its essential to pre-filter through a millbank bag or similar, as I'd imagine a bog pond would clog it up pretty quickly.

 

[little_leaf177]

Cheers Andy.. so its filters and Dilutes the Water?

I found the water was filtered from sediments already but its the tiny little things that got my concern.. just next time I go i'd like to save on the iodine if at all possible... do you think this would be safe enough?? 300 litrs.. that's probably enough for about 1-2 months daily use easy..

 

[Andy BB]

Not sure about diluting it!

But IF their advertising blurb and references can be believed, its probably the only water filter around that will "eat" all bacteria, viruses and reduce heavy metals etc. Two downsides that I can see - you'll need to pre-filter the water first - Millbank bag or similar, otherwise it's life will be massively reduced. Secondly its lifecycle is probably - even prefiltered - limited to 350litres - and I seem to remember reading somewhere that it has a limited life anyway once the filter is first operated.

 

[Bluffer]

Waterborne viruses cause serious illnesses (Hep A, etc) which is why I don't trust many gadgets.

Katadyn filter followed by chlorine diox for me, if you value the health of your liver and other internal organs then £80 or so is money well spent

 

[BillyBlade]

First need xl purifier is certified to EPA Guide Standard for microbiological purifiers against bacteria, cysts and viruses and removes giardia and cryptosporidia. Only does 250 gallons though, then its new cartridge time.

Expensive, but worth it. My kidneys think so anyway.

 

[General Strike]

I can't speak from a position of expertise on filtration, but I think the technology used by Water To Go, Pure Hydration and First Need (possibly others too) is based upon electroadhesion - the filter carries a positive charge, which is the opposite of that of organic material - so although viruses could pass through the filter, they are attracted to the filter medium and stick to it as they approach the pore. They claim to remove much smaller contaminants than viruses, too.

 

[BillyBlade]

I've drank from water sources that looked like death in a puddle after pumping it through the first need. It went into the nalgene tasting better than Evian.

My stomach is my personal weak point, hence why I don't mess about when it comes to water. I really dont rate the oft mentioned favourite: it's a filter, and not a purifier, and there is still the need for chemical treatment before you drink it. People trust it though because the british forces issue them, not realising they may have won the contract but price was a major factor in that. And there was me thinking that mod procurement had finally realised that good stuff aint cheap, and cheap stuff aint good.

Do the 'blue dye' test and you'll see what I mean.

Anyway, I'll get of my high horse now. Good luck with whatever you decide to go for, and stay well. Getting ill from bad water is a horrible thing indeed.

 

[little_leaf177]

Cheers pal - exactly the kind of answer i was after to get my head around how they work...
It was the process which i was curious about rather than if it does/doesn't work. - I've seen first hand how they do work and unfortunately recently how it can go a bit wrong using chems (flooded threads etc.)
I may stick o oth in the future as a precaution along with the knowlege of if needs be it could be safe to drink without chems after its put though the systems. Cheers pal

I can't speak from a position of expertise on filtration, but I think the technology used by Water To Go, Pure Hydration and First Need (possibly others too) is based upon electroadhesion - the filter carries a positive charge, which is the opposite of that of organic material - so although viruses could pass through the filter, they are attracted to the filter medium and stick to it as they approach the pore. They claim to remove much smaller contaminants than viruses, too.

 

[SJStuart]

The LiveSaver filters down to 1nm (0.001 microns) so will not only filter out viruses, but also some chemicals, including radioactive Iodine (131).

Oh and it seems to filter hydrocarbons, too... as I drank from a nasty-bottom puddle on the road which had oil (likely diesel) floating on it... and not only did it not taste of oil, I didn't get sick at all.

I also drank from the River Ouse in Thetford, just down stream of a dead rat (which we only found out was there after I had collected the water) and neither myself nor my friend (who also drank the same water) got so much as a sniffle... not to mention it tasted great

 

[MrTuna44]

Hi,

I can't speak for the other systems, but the APT (Aquapure Traveller) uses a "tortuous path" system. Therefore, it isn't the absolute size pore that counts, but as the contaminants go through this (relatively speaking) large pore, they get trapped in the "corners" and twisting path. A 0.01 micron pore is very hard to get water out of!

 

[army-surplus]

so surviva pure is the best?

 

[Bluffer]

Katadyn are the best.

 

[General Strike]

so surviva pure is the best?

To be honest there seem to be a few firms producing filters that work on broadly the same principles. I would stick to the manufacturers that state that they remove viruses, and cite the School of Tropical Medicine & Hygiene as an approving body, as this seems to be the most credible organisation producing research on the subject - they aren't going to recommend any old cobblers!

 

[Bluffer]

The Katadyn products are licensed to US specifications and are licensed as 'filters' or 'purifiers' depending on their designation and efficacy.

 

[Angst]

hi...i was about to buy a sawyer mini....a third of the price of a katadyn.....any advice on this please?

s

 

[BillyBlade]

Katadyn are the best.

Really now? Based on......?