Ultralight Backpacking Water Filters And Water Purification Methods

backpacking water filters

Unless you have experience drinking untreated back country water, it is recommended that you treat your drinking water by filtering or another method of water purification. Here are some popular ultralight backpacking water filters and water purification methods…

Inline/Gravity-fed Backpacking Water Filters

backpacking water filters

Sawyer Inline Water Filter

Inline backpacking water filters work the same way as pump water filters, but they use gravity or suction to move the water through the filter. Eliminating the pump results in substantial weight savings and requires less effort to filter your water.

Inline backpacking water filters are installed in your drinking tube between the water bladder and mouthpiece, so water  is automatically filtered as you suck it through the line.

Gravity-fed backpacking water filters use gravity to pull water from a bag or bladder, through a water filter, into another receptacle (such as a water bottle, cookpot, or another water bladder).

Like most pump water filters, inline backpacking water filters will begin to clog after continuous use as sediment which is removed from the water begins to accumulate around the filter element.

Inline backpacking water filters like the Sawyer Water Filter include a sink attachment hose so it can be backflushed periodically to reduce clogging. Using an inline pre-filter also helps.

Popular Inline/Gravity-fed Backpacking Water Filters:

Chemical Water Purification Drops/Tablets

backpacking water filters

Aquamira Chemical Water Treatment

Unlike water filters, which remove potentially dangerous organisms from the water, chemical water purification works by killing them instead.

There are many different types of chemical water treatment, but they all work in the same way. You add the chemicals to your water, wait for a pre-determined amount of time for it to take effect, and then drink your water.

Chemical water treatments are simple, lightweight and require no equipment. The downside is they leave a bad taste in your water, don’t remove sediment, some take longer to work than others, and drinking chemicals isn’t really the healthiest thing to do.

Popular Chemical Water Purification Drops/Tablets:

Electronic Water Purification Devices

backpacking water filters

Steripen Adventurer UV Water Purifier

I only know of two of these types of devices…

Steripen uses UV light to kill contaminants in the water. You basically stick it in your water, activate it and swirl it around for 1-2 minutes.

MSR Miox uses salt and electricity to create an oxidant solution which kills contaminants.

The benefits of electronic water purification is no chemical taste and they don’t clog or need to be replaced or backflushed like filters do.

The downside is they require lithium batteries (which have to be replaced quite often). This can become very expensive. A solar charger is one solution to this… but not exactly lightweight.

Popular Electronic Water Purification Devices

Boiling Water

Boiling water is not a very practical way of purifying your drinking water throughout the day, because it would use up lots of fuel and time. But if you are using another type of water treatment method and it malfunctions (like your filter clogs, or you run out of chemicals or batteries) then you can purify water by boiling it. Also, water that is intended for cooking does not need to be purified using other methods (if boiling is part of the cooking process).

Not Treating Water (Try at your own risk)

Many people would have you believe that most of the water on earth has become “contaminated” and must be treated. This is not necessarily true. In many places (especially in the high mountainous wilderness areas far away from civilization) the water is the same as it always has been. The animals that live there still drink the water with no problems.

The problem is not with the water itself, but with human intolerance to natural organisms in water. If you grew up in the city and have been drinking municipal or bottled water all of your life (which has been cleaned and purified to the max) then your immune system may no longer be able to handle natural water. But, if you grew up in a rural area drinking untreated well water like I did, it may be possible for you to drink natural water with no ill effects.

I started out purifying all my water on hikes, but now I only do it rarely. I’ve drunk thousands of gallons of untreated water while hiking and still never gotten sick from it, so I am pretty confident in my ability to handle it. But that is no guarantee that you can do the same.

If you want to do the safe thing, treat your water all of the time. If you want to enjoy back-country water without treating it first, then I recommend starting out slow. Start by drinking only from the cleanest, clearest, high mountain springs. Then, as time goes on, you can experiment with drinking more untreated water from a wider range of sources.

What I Do

I carry two types of water purification (not at the same time):

In low-land regions where water sources are stagnant, near roads, highways, towns, agricultural or industrial runoff or where there are cows, horses, sheep or other livestock grazing nearby I carry a Sawyer Inline Water Filter and use it regularly.

In high-altitude back-country regions where water sources are typically mountain springs, fast-moving creeks and clear snowmelt lakes I do not treat my water. But I do carry MSR Sweetwater Drops as a backup, in case there is a water source that needs to be treated.

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55 Responses to “Ultralight Backpacking Water Filters And Water Purification Methods”

  1. Dude, did I miss something? What about the various pump filters like the ancient PUR I’ve used for 12 years? Also Iodine that I’ve used as a back up from time to time. When I moronically clogged my pump?

    • @Bamboo Bob: I listed iodine under chemical treatments. I did not include pump filters because in my opinion they are too heavy for ultralight backpacking (the lightest I’ve seen weighing around 10 ounces).

  2. How does the MSR Sweetwater drops (what you like) compare to Aquamira drops in taste, health, weight, and purification? I only have experience with Aquamira.

    • @Rockin I believe Aquamira is illegal (or restricted) in California where I live, so it’s harder to find. I’m not sure why it’s illegal but what I have heard is that it is because some people use it to make meth. I have used Aquamira before though and I like it. The main difference between Aquamira and MSR is Aquamira includes the two parts that have to be mixed and the MSR is a single solution that is added right to the water. They both taste about the same to me (better than most other chemical treatments) and work pretty quickly (about five minutes for the MSR and I think not much more for Aquamira). The active ingradient in Aquamira is Chlorine Dioxide and in the MSR Sweetwater Drops it is Sodium Hypochloride (I don’t know what the difference is).

  3. Man, I have been wanting to drink from streams that look so cool, so crisp, and so refreshing, but I have been brainwashed to purify, to purify, to purify. I’ll still dunk my head in, and secretly sip on some of the run off as it drips down my face (and boy, do I feel guilty, like I’ve done something illegal).

    Up in the mountains (I hike the Catskills – NY – nearly every weekend, I’ve often wondered what the consequences of such taboo actions as drinking straight from the stream would be.

    I may have to tempt the gods (and a week off work, if needed) and indulge . . . .

  4. Another method, which is very rarely discussed is SODIS (Solar Water Disinfection) depending on how turbid the water is, and making sure you have non-pet bottles, all you need to do is hang clear bottles or bladders in the sun for a few hours to completely rid them off all the little buggers that make you sick. The UV water purifiers are just a concentrated way of doing this. This method is becoming very popular in developing nations and is endorsed by the WHO (world health org, not the band) For more info to get started you can read here http://en.wikipedia.org/wiki/Solar_water_disinfection

    • I’m pretty sure you have to use PET bottles for the SODIS method to work. At least, thats what the Wiki article says.

      FWIW, I use an MSR hyperflow and I really like it. It can be used as a gravity filter as well by removing the pre-filter and connecting the hose to the bottom of a bladder. Very functional, but it weighs 8oz. I do like having the added versatility of a pump and pre-filter. It makes getting water from dirty or shallow sources very easy, and if you are clever you can use the pump to fill your bladder while it’s still in your pack. Anyone who knows how much of a pain it is to wedge a bladder (full or empty) into an already full pack, knows this is a very handy option

  5. Erik, I thought I might pass along another product. It is the Seldon WaterStick™. Approved by NASA it filters everything 99.9999 % of bacteria and 99.99% of viruses. It is 6.9 Oz and will filter over 70 gal of water before you need to change the filter.

    I also use a SteriPEN™ and I carry both when I am on overnight trips.

  6. Eric, I use a 4″ bio fuel filter for all water sources. Good to 1 micron, weighs a couple of oz., and fast. I carry a Steripen for suspect sources. It fits in my half-liter Nalgen and 45 seconds later I’m sipping away. Never failed yet.

  7. It’s pretty easy to build your own (gravity) inline filter system. I use a Seychelle inline filter, along with a couple platypus bottles. One of the platypus bottles has some cord attached to it (I put some holes in it, close to the bottom). This works for both drinking on the go (stop at a stream, attach the filter and sip) as well as drip filtering (from one bottle to the other).

  8. On a thru-hike my Steripen Adventurer goes for about 3 weeks on a pair of lithium batteries. I can generally get a pair of batteries for about $12. It seemed that others bought Aqua Mira about as often for about the same price. Filter cartridges cost about 3 times that. I’ll stick with the Steripen at under 4 ounces.

  9. Regarding the two types of chlorine treatment:
    Aquamira is what is used by municipal water systems, and (IMHO) has distinctly less aftertaste than bleach, aka sodium hypoclorite, aka Clorox, aka MSR Sweetwater Drops (if you are fool enough to pay an inflated price for re-branded laundry bleach).

  10. Oh, and Aqua Mira is available in Calif via mail order (Campmor). Also there are some independently minded outdoor stores in far Northern Calif that stock Aqua Mira.

  11. When using the Sawyer In-line, do you carry the faucet attachment in the event you need to backflush? Or do you just back up with chemicals in case the filter clogs?

  12. Erik,

    I have the Sawyer inline filter on my camelback and it’s great! I weighs virtually nothing and I can pour water directly from a stream into my camelback, how easy!

    I highly recommend it tom other hikers.

    Handyrock

  13. Scoutboy,

    You’ll need the faucet attachment if you filter water from a dirty source. Otherwise, it’s really not necessary. If you’re on a long distance hike, it’s probably a good idea to have it with you in case you have no choice but to filter water from a particularly dirty source.

    Handyrock

  14. @StormKingHiker I know how you feel. Nothing beats a drink of fresh mountain spring water on a long hike

    @Matt Thanks for the heads up on SODIS. I hadn’t heard of that, but it sounds like a good way to purify water in a emergency or when you have plenty of time at camp

    @Robert Thanks for the heads up on the Selden filter. It looks to be bit heavier than my Sawyer (6.5 oz vs. 2 oz) but still lighter than most pump filters

    @Bronco Do you have a link to a website for your filter?

    @RossB Building your own gravity system does sound like a better and lighter solution than some of the commercially available ones. One thing I always wondered when connecting two bladders together: Do you make a way for air to escape the system as water moves from the full bladder to the empty one, or does it have to travel back up the hose?

    @Voyageur That is pretty good battery life for your Steripen. I had one of the first Steripen Adventurers that came out a few years ago and remember having to replace the batts about once a week. Of course that was in the desert and I drank a lot of water. At three weeks for a set of batts and only 3.5 oz the Steripen sounds like an pretty good option again.

    @Watertank Thanks for explaining the difference between Aquamira and MSR Sweetwater. I knew you could use bleach but didn’t know that MSR drops were the same thing. Now that I look at the price $14 is pretty steep compared to a buck at the grocery store. I use it so infrequently that I still have half a bottle left after two years, but when it finally runs out I may give regular bleach a shot, or order some Aquamira.

    @Scoutboy I don’t carry the faucet attachment for the Sawyer but I do keep it in my bounce box (box sent from town to town) so I can backflush it periodically. Usually the clogging doesn’t happen right away, but over time. When it starts to get harder to suck the water through the tube then you know it’s due for a backflushing.

  15. Are you just immersing your drinking bladder in a pond or stream? How do you do the prefiltering in high sediment areas?

    In general, chlorine dioxide is safer for human consumption than sodium hypochlorite. I use c.dioxide tabs for backup. I’m not sure the bleach sold for laundry is industrially pure, ie produced with the same standards of purity as something produced for human injestion. I know people use bleach in disaster situations but some manufacturers may care more than others about purity.

    • @Maxine Sometimes I dip the bladder in the water. I also carry a water bottle for getting water from shallow ponds and whatnot (if it’s really shallow I’ll use my cooking mug because it has a flat side). I carry a small piece of no-see-um mesh which can be placed over the top of my water bottle to filter out really heavy sediment like big sticks and leaves and stuff before pouring into the bladder and being sucked through the inline filter. I have tried using a bandana for pre-filtering as well (which I have heard suggested before) but it didn’t work that well. The cloth was too dense and it took a long time for the water to soak through.

  16. I am hiking the JMT from TM to WP in August and want to use the Sawyer. I don’t think I will carry the faucet attachment, but carry MicroPur tabs as my backup.

  17. I am an Emergency Physician with 38 years experience and have done much long distance hiking for 30 years.
    Almost all diseases spread by water are from other humans.
    Dilute germs are too weak to infect.
    Giardia takes 1 week to cause diarrhea, can be treated most of the time with metronidazaole, and goes away in a few months.
    The are very few fatal diseases spread by water other than severe diarrheas, which can be treated with salt solution by mouth or intravenous.
    I have drank spring water and stream water upstream from human habitation without getting sick in mountains here and even in Nepal.
    I have met few hikers who have gotten sick.
    I agree with Erik’s methods.

  18. The Aquastar UV system costs less than the Steri-pen and the company donates the units to disaster areas (so you can support a good cause and get a great system at the same time). I hope you add that unit to your list.

  19. Hey Erik!
    Once again thought I’d chime in about my own adventures with water consumption. I grew up in Minnesota- drank rural water from a well that has since been declared contaminated (agriculture chems)- also drank from more than my share of Minnesota lakes while swimming- have never been sick from any such consumption. However, DID get confirmed giardiosis from municipal water in Sacramento CA. For back country use, I use a typical Katydyn Hiker Pro if I know the water is going to be really bad, and Aqua Mira if it’s not. In So Cal I use both, due to my own digestive issues now. I haven’t noticed any bad taste with Aqua Mira. I am definitely game though in perhaps updating with an inline filter to replace my heavy Katydyn, who has been my faithful trail companion for years. Thanks for another great idea!!

  20. @Maxine and Erik- I agree regarding bleach purity issues. Maybe I shouldn’t have been so quick to poo-poo the MSR Sweetwater drops. I’m sure that the MSR drops must have a higher level of purity than generic bleach. However, in the rare instance that I do use bleach, I would opt for real Clorox bleach.

    @Dr. Andy- Would you consider it prudent to carry metronidazaole on an extended backpack trip in the continental US?
    And, I know it’s a bit off topic, but I’d like to hear you your opinion on carrying snake anti-venom. With thousands of miles of trail time, I’ve had a few close calls with rattlesnakes, and would consider rattlesnakes my biggest trip-ending fear.

  21. Hi Erik,

    I liked your info on water purification. Have you ever looked at using Grapefruit Seed Extract as your backup liquid. I used to get sick occasionally even when just traveling for business and drinking from local water supplies. This stopped about 10 years ago when I start carrying a small bottle of GSE by Nutribiotic with me and always putting a few drops in my water before drinking. I’ve not yet used it on a hiking trip, but I think it might also work as a nice simple purification backup, probably as good or better than those chlorine drops you carry.

    Here is a URL for the nutribiotic items — there may be other suppliers too: http://www.nutribiotic.com/gse-liquid-concentrate.html

    Happy Hiking!
    Chuck

  22. Erik, Thanks for your comments about drinking "un-purified" water. I have drank unpurified water from various Sierra streams, Nepal (where Sherpas lug bottled water to 17,000 feet for the Everest trail hikers) and the jungles of Borneo (this was probably a very bad idea) and I never had any problems. I also recall a US Forest service study from about 20 years ago that found approximately the same number of giardia cysts (less that one per 100 ml) in San Francisco’s water supply as in the 20 Sierra streams they sampled.

  23. You have mentioned the Aquamira tabs, have you or anyone used the Aquamira filters in their water bottles? And if so are they reliable?

  24. 1) Hanging a bottle in the sun doesn’t kill a lot of stuff and in fact some nasties thrive in visible light. UV will not penetrate any bottle that I know of, so don’t think about natural UV.

    2) I have cut my pack weight by using a Steripen. I was using AaquaMira until I realized that I was carrying extra water to make up for the treatment time.
    With the steripen, I don’t have to carry so much water and can tank up at the source.

    You can save a significant amount of money using the classic AA version of the Steripen over the other models. It weighs an ounce or two more, but you can go 8+ times longer on one set of batteries. One set of 4 AA lithium batteries cost about the same as two of those little CR123 batteries.

    3) Some small municipalities do use an industrial version of the Steripen for water treatment.

    4) Experts agree, you must wait 30 minutes to 4 hours or more to kill giardia and other bigger organisms when using chemicals. That means you have to carry that water quite a ways before you can drink it. UV works immediately so drink at the source and carry less when you hike.

  25. Bushwhacking Fool Reply May 11, 2011 at 9:30 am

    I typically use two different filter techniques(and yes, I often carry them at the same time). My main one is the Sawyer Inline Filter with two Platypus bags and some tubing. Often I pre-treat the water with Aquamira before running it through the filter to kill any possible viruses. Since I do most of my backpacking in the Adirondack low-lands I find this double-whammy method works well. When I was out in the Sierra-Nevada Mountains in 2009 I only used the Aquamira drops though.

  26. Erik,

    I am intrigued by the gravity fed filter, and I was wondering just how easy it is to fill a bottle from the line. With it being gravity fed, and chances are it is in your pack, how do you get the line down so that it has sufficient pressure/suction to pull the water through the filter?

    If it is a hassle would it be worth it to bring a large syringe, one that is big enough to fit into the mouth piece and pull out say 100ml at a time?

    • @Jake Gravity fed water filters rely on gravity to pull the water through, and the ones I have used are pretty slow. But the system that I use (Sawyer filter inline between water bladder and mouthpiece) doesn’t need gravity because it relies on suction. You just suck the end of the tube and filtered water comes through. It doesn’t require any special placement of the components and it’s not really harder to suck than drinking from a water bladder normally is (except when the filter starts to become clogged, which occasionally backflushing will solve).

  27. Which Sawyer filter do you suggest for an AT thru-hike?

  28. Hi Erik,
    You said:”if it’s really shallow I’ll use my cooking mug because it has a flat side” to scoop out the water but if you do that aren’t you going to contaminate the mug? Even if you boil water in it later on you will still have some “bugs” on the walls inside your mug and as you drink you might swallow them.
    Thank you.

    • @Barbara: I suppose scooping it up with a cup might “contaminate” the cup. I try not to take water from sources that are shallow or stagnant, so it’s usually not an issue. I think that the paranoia about drinking water in the backcountry is similar to the germaphobia a lot of people have these days. The supposed risks (and measures taken to avoid them) are sometimes a little excessive.

  29. It could contaminate the mug, but there would be such a small quantity of the bad organisms that they would be harmless to your system.

    The body can natural rid itself of small quantities of the bad organisms.
    It’s when you drink water that contains many that your system gets overwhelmed and you get sick.

    Otherwise people would get sick from swimming and bathing in wilderness bodies of water.

  30. Hi Steve and Erik The Black
    Thank you for your responses. I am not normally “paranoid” (LOL) but I have never drunk water from the nature so I do not know what to expect. I am new into backpacking and to be honest I did not think too much of water but then you read some articles, posts that can make you worried. Sometimes it is hard to know what info is good and what is not and I do not want to find it out the hard way. For example, do I need to use treated water to wash my dirty pots? I did not think that it was the case but then I found that some people say that you have to use treated water for dishes. I would think that as long as the water is not visibly icky then it should be OK to wash dishes with it? What do you guys think?
    Also I have read about someone using Steripen and getting sick. Maybe they did not use it properly?

    Thank you in advance.

  31. Stevie McAllister Reply August 15, 2011 at 2:45 pm

    @Barbara,

    Any method can fail if not used properly. Another thing to consider is that people may think they get sick from the water, when they might have become sick from another source.

    I remember hearing of a whole group of people hiking together on the AT. All came down with intestinal something or other that they attributed to a failure of their water treatment method even though they didn’t all use the same system. They later realized they probably got it from staying in the same shelter as someone who was already sick with the same ailment.

    UV treatment has proved to be one of the most reliable as it is difficult to screw up when using it and it works on all living organisms.

    There have been many scientific test comparisons and articles on the subject.

    Realize that you can consume small amounts of giardia and chrypto without adverse effect.
    There have been many tests on this subject. Google can show more details.

  32. Great blog! Since you already said you’ve never been sick yourself, have you ever heard of someone getting a virus through filtered only water? From what ive read bacteria will not pass through but filter elements are not small enough to capture viruses.

    Im a iodine packer but cant stand thr taste, but going filtered only sort of freaks me out a bit.

    • @Paul: I have known hikers who, despite being very diligent about treating all of their water, have still come down with giardia-like symptoms. But I can’t be certain that it was always related to water. As Stevie mentioned, hikers sometimes attribute any kind of flu-like sickness to bad water when it can be caused by other things. Most go to a doctor, take some medicine and are back to normal within a week.

  33. Yeah, I agree we all tend to think first “what did i eat?” When in reality its nothing to do with the assumed culprit.

    I “knock on wood” have not yet had an ailment from swallowing untreated water or treated water. Ive also wondered if growing up on well water for 18 years had anything to do with it! I beleive e coli frequent wells especially in areas involving cattle grazing, which was right next foor.

  34. rj lewis i live in sacramento for over 30 years and you are right the city water taste like crap it looks clean but tast like old dish water proablly due to most of the water lines being over 80 yeas old fortunatly they are starting to rupture and being replaced in the mean time i only use tap water to bath and wash dishes with

  35. Hey Eric,

    I really like the idea of inline filter, as well as its weight and price. Here is my concern. It sounds like the inline is primarily a personal water filter. If I go backpacking with my girlfriend or dog, I need something to filter their water. Apparently, you can use the thing like a gravity filter by putting one end of the hose in a bottle. Does this work well? How long does it take? Should I consider something else?

    • @Josh: If you splice the inline filter into the drinking tube attached to a water bladder (like a Platypus) you can detach the half of the hose that leads to the mouthpiece and squeeze the bladder to force water through the filter into any receptacle.

  36. Eric,

    After years of using a pump filter, I’m in the process of switching to an inline one. I’m curious about your use of an extra water bottle, such as a Powerade bottle. How do you work that into your drinking/cooking routines? Also, can I assume that you gravity filter into the bottle?

    • @Robert: I rarely treat my water any more. I just drink it untreated. I think after years of drinking back country water I have a cast iron gut, so it doesn’t affect me. But when I did use the inline filter more often I just spliced it into the drinking hose from my Platypus bladder, so the water gets filtered automatically as you suck it through the tube. If you need to get filtered water into another container (like a water bottle or cookpot) you can disconnect the half of the tube that goes from the filter to the mouthpiece, and just squeeze the bladder to push water through the filter and into whatever container you like.

  37. Yep @ErickTheBlack your body learns to adapt. I drink the water in Nicaragua and Costa Rica and never get sick whereas other gringos do who arent used to it.

  38. I’m getting ready to go to Nepal to do some hiking and back packing. I’m looking at the Sawyer squeeze water filter to attached to my cord on my bladder (backpack) would that be ok or do I need the Sawyer 3 way inline water filter instead?

    • @Mary Conway: I believe the filtration mechanism is the same for the Sawyer squeeze filters and the inline filters. The difference is how you get the water. With an inline filter you suck on the drinking tube and the water is pulled through the filter into your mouth. With a squeeze filter you squeeze the water from one receptacle into another. If you like drinking from water bladders the inline would probably be the better choice. If you like drinking from water bottles the squeeze might be the way to go. Have a great trip!

  39. I am available for advice on Nepal and Alpine trekking.
    brocc7@hotmail.com
    206-547-0161

  40. Erik said:”MSR Sweetwater…I use it so infrequently that I still have half a bottle left after two years”

    Bleach (MSR Sweetwater drops) does not have an infinite shelf life, not even close- especially in thin plastic containers. If following standard purification doses, the most common advice is to use bleach less than 90 days old . In an emergency, increased quantities of older bleach can be used. Bleach is so cheap and available, might as well just buy a new bottle at the store- make sure to get the unscented kind.

  41. This is a very good idea. I love to travel from mountains and I always afraid to drink from spring water because I was afraid to become sick. This will solve my problem.

  42. IMO filters are too heavy use up too much space and are prone to user error

    I use a 1 micron mesh over our water bottles to get out any gunk and then treat with aquamira……done and done and probably the most fool proof solution out there.

    Just remember to get to get the treated water into to the water bottle cap threads by gently shaking with the cap a little loose or else you could get sick from the untreated water left in the thread area from dunking.

  43. how about the Sawyer filters?

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