Water Filtering/Purification – Which to choose?

"And I ask this all the time. How do you know if a chunk of hollow fibers cracked or broke (from freezing or dropping). If it’s a large break, then the water all of a sudden flows faster. If it’s a smaller break, then ask a University to do a scientific analysis. Hopefully they do it for free :)"

This bugs me too! One of the reasons I'm still with our trusty Katadyn Pocket… As it is always two of us on a hike I can just about justify its 20oz weight (10oz per person).

I also decided not to bother about filtering viruses. If its a stream from Scottish highlands there won't be any. If its a muddy stale water I would normally want to boil it anyway after filtering.

First Need uses an electrostatic charge to capture viruses.

It DOES NOT filter them.

Life Straw likely uses chemistry, as it is not as complex a mechanism.
http://www.rei.com/learn/expert-advice/water-treatment.html

There are no filters for viruses.

"And I ask this all the time. How do you know if a chunk of hollow fibers cracked or broke (from freezing or dropping). If it’s a large break, then the water all of a sudden flows faster. If it’s a smaller break, then ask a University to do a scientific analysis. Hopefully they do it for free :)"

that's what I hate about hollow tube filters like Squeeze

Sawyer says, if you think it might have froze, continue to use on that trip and then get a new one

Too bad there isn't a solution of colored particles a little bigger than the pore size. Filter it and see if the color goes through filter. I have heard you can do that with food color, but that doesn't make sense because the dye particles are much smaller than the pore size.

You can shake out the water outside the tubes. The water inside the tubes should be okay to freeze, because the tubes are designed to expand a little when you backflush. The filter should be able to withstand freezing. Too bad they don't test that.

"There are no filters for viruses."

Lori P, you are mistaken. Have a look at Lifesaver – the link above- it is just one of the examples.

"First Need uses an electrostatic charge to capture viruses.

It DOES NOT filter them."

Personally speaking I think its best to leave wordsmithing out of these conversations. It only confuses people. My .02

On Topic:

My group usually uses a platypus gravityworks, but we have a group of 4 or more usually. For two people it may not make sense to carry the extra weight when you don't need that volume of filtration. On the flip side of that argument, its nice to be able to be a little frivolous with your clean water when washing dish etc.

Like people here have said, picking a good water source is key. If you have a good water source any of your choices will work.

Since as you said your new to this topic, I'm want to state what most people here would consider obvious. Do not mix dirty and clean water containers. If you put "dirty" water in a container do not turn around and fill it with clean water and drink from it. I know it sounds obvious, but I have seen people do it.

@NJDrew – Thank you!

@Lori – I have to agree with @NJDrew, you are adding more and more confusion to this thread by splitting hairs over dictionary definitions.

In the case of the Frontier Max they call their entire system a filter even though as you eluded to they use a electro-positive charge inside their cartridges to get the job done.

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For everyone else as a quick recap.

There presently two known options presented in this thread that meet the requirements of filtering bacteria, protozoa and viruses that would be viable for backpacking (See below). Other solutions exist which filter the same, however I don't believe any of them thus far have a real portable solution beyond a filter in a bottle.

1) aquamira Frontier Max – http://www.aquamira.com/products/frontier-max-filtration-system/
2) LifeStraw Mission – http://www.buylifestraw.com/en/products/lifestraw-mission

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Thanks again everyone for the awesome help!

Great to be of help, Lane. So, next steps are to order the Frontier Max — and then report back please. Inquiring minds want to know the weight and dimensions — and how easy it is to suck water through that filter/ static charge whatchamacallit. :)

You got it, will likely be a couple weeks yet while I finalize my gear list (I am brand new to backpacking).

Rapidpure filters claim to remove bacteria, protozoa and viruses using electrostatic technology. Numbers look good if you trust the tests.

Never heard of it… until now. Looks good! Surprising that adding more filters will increase overall flow rate!?!

Not adding more filters, just larger filter elements in expandable housings.

OK, I see.

Apparently there is an article here on BPL – http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=95503

Or simply click HERE

Nice — thanks, Lane!

You and you fancy links!

The Rapid Pure and Aquamira systems are nearly identical in pricing for both the main systems (Scout and Frontier Max) and I believe filter nearly the same volume of water before replacement filter is needed.

Initial Cost
Aquamira Frontier Max – $37.00
Rapid Pure Scout (1.2L) – $38.73

Replacement Filters
Aquamira Frontier Max Replacement Filter – $27.43
Rapid Pure Scout (1.2L) Replacement Filter – $26.95

Volume per Minute
Aquamira Frontier Max Volume – 500ml/minute
Rapid Pure Scout (1.2L) Volume – 1.2L/minute

Weight
Aquamira Frontier Max – 6.4 oz.
Rapid Pure Scout (1.2L) – 2.7 oz.

So the Scout from Rapid Pure weighs half as much, filters over double the volume of water per minute and costs nearly the same as the Aquamira Frontier Max on both initial and replacement filters.

The Scout also has an extra "9" in their 99.9999% too over the Frontier Max.

I think I will be grabbing the Scout instead and trying it out first.

I believe the rapidpure scout is supposed to last for something like 1500 liters, but as always, YMMV.

I played with a 1.2L Scout as gravity filter (in my back yard) and it seems to work OK. Seems to need at least a few feet between the resevoir and the filter to get decent flow rates. The plastic bubble like housing needs to fill up with water to get the faster rate. I noticed that sometimes it would only fill up 1/4-1/3 the way, effectively cutting the filter size available to filter and the flow would be slow. Get the housing full enough to cover the whole filter element and the flow is faster.

Have you tried in line with a bladder at all by chance?

Yeah, how much sucking effort does it take? Thinking… somewhere up the Mt. Whitney trail…

"Have you tried in line with a bladder at all by chance?"

No but I don't see a reason it wouldn't work. The shape of the housing is wider that other filters like the Sawyers so perhaps a little more unwieldy but otherwise I would suspect it to be an easier draw than with the Sawyers.

The Sawyer 0.02 filters have an absolute pore size of 0.02 micrometers and thus FILTER viruses commonly problematic for drinking water. It is a bit slow, though, at about 5 minutes per liter when not clogged. I use one when wilderness traveling with my 7 year old.