Water Filters: Squeeze vs Pump vs Gravity

[DayTrip]

I've been getting peppered with so many 20% off coupons from various outdoor companies the past few weeks that I've been doing a pretty thorough review of everything I carry and whether or not I can upgrade anything to a better/lighter/more efficient version. I was reading a SectionHiker article about filtration and it got me wondering about this. I current use the Sawyer squeeze type filter which is pretty light, simple and while not crazy fast has been fine for what I've used it for. But with the intention that I will be camping/backpacking more this year I'm wondering about a faster option to generate more drinkable water in the same or less time. Filling several Nalgene's with the Sawyer can be a significant time delay.

Pump types like the Katatdyn Hiker Pro seem to be much faster producing water and the design seems like it would be far more efficient sucking water out of puddles, standing water and other smaller sources that attempting to fill a squeeze bag in would be difficult/take forever/maybe impossible. Are pump styles really that much faster than squeeze models? I believe it said that 48 pumps a minute produces 1L of water. And what about the "field maintenance" in the description. Should I read that as "breaks a lot in the field so it's designed so you can fix it"? Is that mechanical pump likely to break (the unit is so light I wonder if the plastic is not cheap and prone to breaking).

And what about gravity units? The Platypus model I looked at said it is capable of producing 4L of filtered water in 2.5 minutes. Is that for real?? That seems to good to be true. I could see where that would be a huge advantage. Just tank up the bag and let it create water while you're doing other stuff like putting up tent, eating if on a rest stop, etc. It would have the same obstacles filling the bag in smaller sources but for that kind of speed it might be worth the aggravation. The unit is not that heavy either and I believe there was a 2L version. And with the fittings that apparently go directly to many hydration packs this seems pretty useful.

Anyone care to elaborate on the benefits/pitfalls of the different types, make a pitch for their favorite, etc? I'd likely use mine for 75% day hiking and 25% backpack camping.

 

[Gremlin]

I use the First Need water filter (Google), it also eliminates viruses. You can order a tube and prefilter, but I got a tube from the local pharmacy and a pre-filter from campmor.com. I got hepatitis A twice as a kid and now I want the best protection. First Need is the only way to go. Trust me.

 

[Peaks]

If you are a backpacker, then weight is frequently the deciding factor

 

[nartreb]

I use the Katadyn hiker. It's small and light. Doesn't pump as easily as some but it's fine for solo or small groups where you rarely need more than a few liters at a time. Can't remember the last time it needed any maintenance. Shape of the prefilter mean it needs about an inch of water to work, though you could easily remove or partially tape over the prefilter so it could work (less efficiently) in a few mm.

 

[peakbagger]

I and many others concerned about weight and reliability stick with Aquamira. A filter is inherently a convenience decision. Some people push the ick factor for using filters over AQ but a filter is going to need frequent back flushing if used on water supplies with a lot of suspended solids (like many water sources at BSP including chimney pond).

The reality is most backcountry sources, if selected with some common sense, will not make the vast majority of hikers with normal immune systems ill. Despite a prior posters issues with viruses, generally North American backcountry sources are regarded as low potential for virus carryover. If that is a concern, First Need filters do take out viruses albeit with a much higher backflushing frequency versus using AQ. Folks forget that MSR used Millipore filters for virus removal on one of their earlier pump filters and most folks quickly figured out they could leave out the millipore filter and just use the activated carbon filter.

Speaking of the ick factor, most research indicates that the vast majority of US backcountry water illness's are caused by poor sanitation practices. Giardia and crypto are both far more likely to come from fecal/oral transmission within the hikers group. In theory using a pump or chemicals enforces some level of thought in the process and hopefully leads to better hygiene practices. The biggest back country illness by far in the east appears to be Norovirus with outbreaks all along the AT over the last few years and I expect tick bourn illness are the biggest long term issue for hikers.

AMC used to pull water straight out of the so called "underground water sources" at the huts but its become apparent in the last few years that they are adding some sort of chemical treatment. I use the "quote" marks as my observation of many of the AMC hut water supplies as they are not what most folks would regard as deep wells with some sort of packed aquifer supplying the well. They are much closer to a surface supply with some limited coarse filtering at some of the huts but they also practice watershed management around the well fields so the potential for contamination is low.This may be to eliminate potential contamination in the water supply or it may be to introduce "residual" treatment in the downstream piping. It is interesting that AMC hasn't has a few Noro events yet.

One method luckily falling out of favor is chemical treatment is iodine. For many folks including myself it introduces GI issues and for a small portion of the population can be an issue over long term use (weeks of months).

 

[DougPaul]

One method luckily falling out of favor is chemical treatment is iodine. For many folks including myself it introduces GI issues and for a small portion of the population can be an issue over long term use (weeks of months).

FWIW, I have used iodine with no problems*. According to the section on water treatment in Medicine for Mountaineering by Wilkerson et al, it is effective and few people have problems with it when used properly. (It was tested on city sewage...).
* I use tincture of iodine in a dropper bottle. (Tincture has its pros and cons--see Wilkerson for details.)

According to Wilkerson only 4 methods are suitable for wilderness water disinfection:
* heat
* combined microfiltration and chemicals
* chemicals alone (but a multi-hour contact time may be required)
* UV

Boiling is very effective against the standard list of pathogens. One only needs to bring the water to a rolling boil at low altitudes. (Up to several minutes for higher altitudes.)

Filters are good at removing bacteria but let viruses through. 1 ppm of iodine (too little to taste) will do a good job of killing the viruses. A number of "purifiers" use a filter followed by an iodine-containing resin.

Chlorine dioxide (Aqua Mira and others) is effective, but may require contact times of up to 7 hours in cold water to kill cryposporidia.

Iodine in concentrations of 4--8ppm is good at killing everything except for cryposporidia. (I believe it works against crypto with long contact times, but I don't have a reference at hand.)

Activated charcoal is good at removing some chemical contaminants and odors, but will not purify water by itself.

UV radiation (eg Steripen) is also effective.

Note that the required contact times for the above methods depend upon a number of factors including the concentrations and water temperature.

Wilderness water in the NE may mostly be safe to drink without difficulties**, but one can never tell--there plenty of stories of people finding dead animals in a stream above where they just obtained water. Streams that run near trails would tend to be at higher risk and shortly after heavy rains could also be a riskier time because the runoff could wash surface fecal material into the water. It is your choice how careful you want to be. (As peakbagger notes, backcountry illness is more often caused by infection from other hikers, so wash your hands, use hand sanitizer, and pour out your gorp instead of reaching your hand into the bag etc. Just like you should do at home...)
** Water in some other parts of the world can be so contaminated that ingesting only a few drops can cause serious problems. One must treat everything in such places...

I strongly suggest that interested people get a copy of Medicine for Mountaineering[/b] by Wilkerson et al. It covers this subject in a lot more detail as well as having a lot more info of interest to any serious hiker.

Doug

 

[jfb]

Here's a review of different filters: http://www.outdoorgearlab.com/Backpacking-Water-Filter-Reviews

 

[Raven]

I have a Katadyn Hiker Pro. Easy to use and pumps fairly fast. I don't carry it often as I haven't done much backpacking in the past few years, but it has been reliable when needed. It has a very good reputation FWIW.

 

[iAmKrzys]

I started with Sawyer Mini as it was cheap and a lot of people seemed to be happy with it. Having said this, I don't quite trust the water filters. I think that lots of positive on-line reviews does not necessarily mean that the filters are really working, it could just mean that most of the time the water was not contaminated to begin with. The thing is that I don't really know if for example my filter does not have a manufacturing defect. I don't have a water testing lab at home that I could use to tell with certainty that I put in water with Giardia and crypto and none of the comes out. As far as I can tell from reading http://www.outdoorgearlab.com/Backpacking-Water-Filter-Reviews/How-We-Test Outdoor Gear Lab did not test actual effectiveness of the filters either.

For that reason I supplemented my Sawyer with SteriPen. At least with SteriPen it is trivial to tell if the UV lamp is working or not. There is still a question if I get pre-filtering done right but I think it is easier to tell if the water looks cloudy or not. If pack weight and filtering speed is not of significant concern I carry and use my Sawyer to do pre-filtering. To speed up Sawyer use I bought bigger 32 oz squeeze bags that can also serve for water storage if there are issues with water sources along my route. To deal with small bodies of water I actually use 8 oz empty water bottle to fill Sawyer bag - otherwise I found it hard to fill in water that was not flowing. Separately, SteriPen can be used in winter while I am concerned that water in my Sawyer filter will freeze up and damage the capillaries.

 

[DayTrip]

I started with Sawyer Mini as it was cheap and a lot of people seemed to be happy with it. Having said this, I don't quite trust the water filters. I think that lots of positive on-line reviews does not necessarily mean that the filters are really working, it could just mean that most of the time the water was not contaminated to begin with. The thing is that I don't really know if for example my filter does not have a manufacturing defect. I don't have a water testing lab at home that I could use to tell with certainty that I put in water with Giardia and crypto and none of the comes out. As far as I can tell from reading http://www.outdoorgearlab.com/Backpacking-Water-Filter-Reviews/How-We-Test Outdoor Gear Lab did not test actual effectiveness of the filters either.

For that reason I supplemented my Sawyer with SteriPen. At least with SteriPen it is trivial to tell if the UV lamp is working or not. There is still a question if I get pre-filtering done right but I think it is easier to tell if the water looks cloudy or not. If pack weight and filtering speed is not of significant concern I carry and use my Sawyer to do pre-filtering. To speed up Sawyer use I bought bigger 32 oz squeeze bags that can also serve for water storage if there are issues with water sources along my route. To deal with small bodies of water I actually use 8 oz empty water bottle to fill Sawyer bag - otherwise I found it hard to fill in water that was not flowing. Separately, SteriPen can be used in winter while I am concerned that water in my Sawyer filter will freeze up and damage the capillaries.

I use my Sawyer with 2 64 oz bags and will filter as much or as little as I need between stops. Allows for quite a bit of flexibility. Those bags can be a pain in the ass to fill in still or low water though. And while I've never had an issue with the bags the caps aren't water tight and it just seems like they'd puncture or split in your pack as they get older. Would rather pump water directly into a Nalgene and having the ability to pump out of low or stagnant sources increases the opportunity to filter versus packing the water weight.

I guess my reservation with Katadyn is the larger filter size (I think 0.3 microns vs 0.2 microns). Not sure if that means anything relative to giardia and all the other evil things we're trying to filter but it stands out as the worst of all the filters I've looked at.

 

[jfb]

I guess my reservation with Katadyn is the larger filter size (I think 0.3 microns vs 0.2 microns). Not sure if that means anything relative to giardia and all the other evil things we're trying to filter but it stands out as the worst of all the filters I've looked at.

From what I know about filter media, the holes are not uniform and many particles of 0.2 microns and smaller will be captured in a filter rated at 0.3 microns.

I have the old PUR hiker and my only complaints were that it can be tricky to find a good spot to set down the Nalgene bottle where it will not tip over while pumping. I use a string around my neck and hang the bottle while pumping. The other problem was that the vent groove on the side of the stopper was not large enough and the stopper would pop off the bottle while pumping. I drilled a small hole through the stopper at the top of the groove.

 

[VTskier]

I formally used a MSR pump filter, but at over a lb I switched to the small Sawyer last year. I use a 32oz softbottle for the dirty water and filter directly into my hydration bladder. Seems to go just as fast as my MSR pump.

Another option if you use a hydration bladder, and I may try this this season, is to just use the Sawyer inline with the bladder hose. So you use fill the bladder with dirty water and filter as you drink. That would be the fastest method if you want to keep on moving

 

[bignslow]

Another option if you use a hydration bladder, and I may try this this season, is to just use the Sawyer inline with the bladder hose. So you use fill the bladder with dirty water and filter as you drink. That would be the fastest method if you want to keep on moving

I would be very interested to hear from anyone who uses this method.

 

[DougPaul]

From what I know about filter media, the holes are not uniform and many particles of 0.2 microns and smaller will be captured in a filter rated at 0.3 microns.

The size of the largest holes through the filter is the important parameter, not the minimum or the average.

Doug

 

[VTskier]

OP - you mention gravity filters, you can use your Sawyer as a gravity filter. Just get a large bag for the dirty water, and hang it up. I find the Sawyer very versatile and the price/weight is great

 

[iAmKrzys]

I would be very interested to hear from anyone who uses this method.

My backpacking buddy told me recently that last year he saw some hikers drink out of (squeezable) bottles with Sawyer filters screwed onto them, however, he did not know what bottles these were. I suspect most bottles have different threads and I don't know which ones match Sawyer filters but I bet you can find that out if you ask Google for help.

 

[egilbe]

My backpacking buddy told me recently that last year he saw some hikers drink out of (squeezable) bottles with Sawyer filters screwed onto them, however, he did not know what bottles these were. I suspect most bottles have different threads and I don't know which ones match Sawyer filters but I bet you can find that out if you ask Google for help.

Smart Water bottles are most commonly used, but just about any water bottle will fit the threads.

http://ladyonarock.com/2013/11/14/gear-review-sawyer-mini-water-filter/

Just one review I found

 

[jfb]

The size of the largest holes through the filter is the important parameter, not the minimum or the average.

Doug

The filter's rating is determined by the size of the largest hole. Choosing a filter depends on what you're trying to remove and other factors.

If I'm trying to remove particles that are greater than 0.5 microns, then either filter will work, but the 0.2 micron filter may have a lower flow rate and clog sooner than the 0.3 micron.

 

[DayTrip]

I would be very interested to hear from anyone who uses this method.

I had seen this article on Facebook or somewhere you may find useful : http://www.hawaiigirladventures.com/2014/06/diy-inline-water-filter.html It is a "how to" article with step by step instructions and photos.

 

[DayTrip]

My backpacking buddy told me recently that last year he saw some hikers drink out of (squeezable) bottles with Sawyer filters screwed onto them, however, he did not know what bottles these were. I suspect most bottles have different threads and I don't know which ones match Sawyer filters but I bet you can find that out if you ask Google for help.

The Sawyer filter screws on to lots of bottles, including almost all standard plastic soft drink bottles up to 2L. Evernew bags makes a line of bags that are Sawyer compatible too: http://www.evernewamerica.com/overview-1-1-1-1-1/