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Gravity filter vs. Aqua Mira: The age-old question
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David Poston
(dgposton) - F

Locale: Texas / Colorado
Gravity filter vs. Aqua Mira: The age-old question on 06/20/2013 08:44:42 MDT Print View

A few years ago, I posted a thread about piecing together your own gravity filtration system:

I eventually settled on a Sawyer-based gravity filtration system, which I've been using for the last 3-4 years with good success. My current system weighs around 6.0 - 6.5 oz depending on the length of the "dirty hose" I decide to use (longer hose = shorter filtration time). (When I get a chance, I'll post pics).

Now I'm looking at lightening my pack further, thus doing away with a filter altogether. I'm vaguely aware of the Sawyer squeeze that came to market not long ago, but the inconvenience of having to squeeze a bag to get water doesn't sound too appealing. Also, I've read that the bags are not very durable.

I know that the tried and true method for UL backpackers is AquaMira drops. The real concern holding me back, though, is that the instructions state that you must wait a minimum of 4 hours to kill all protozoa, in particular Cryptosporidium. I do most of my hiking amongst the high mountain streams of Colorado, but still the concern remains. Will I be drinking safe water? There are also the occasional situations where the water is murky and is full of particulates, so I'd also want a method to address this as well.

I'm hoping some of you here can allay my fears. Anecdotal evidence stating that person X drank water Y that underwent treatment for less than 4 hours (or was untreated altogether) and did not get sick isn't very reassuring, simply for the reason that the argument, there is an X, X didn't get sick, therefore for all X, X won't get sick is clearly invalid. I'd feel at least a little more confident if there were some scientific studies in which they directly introduced Cryptosporidium into water, treated it with AquaMira, and then demonstrated that all said Crypto were no longer virulent. I've been scanning articles here and haven't yet come across one that directly addresses this issue, but perhaps I haven't looked hard enough. I think the bottom line is: What is the minimum time I'll need to wait to drink safe cold mountain water? If the answer is on the order of hours, then I'm sticking with my gravity system. Filtration takes all but 5-10 minutes, then I can drink to my heart's desire, keep a 1 L of water in my bladder, and hike on. With a chlorine dioxide based system, it seems I'll be carrying my water for a while before I can drink it. Thoughts?

Edited by dgposton on 06/20/2013 08:50:25 MDT.

Nick Gatel
(ngatel) - MLife

Locale: Southern California
Re: Gravity filter vs. Aqua Mira: The age-old question on 06/20/2013 08:58:21 MDT Print View

I have never owned or used a filter of any kind.

Aquamira tablets work much faster than drops, but crypto is still a time concern.

How I manage water

Greg Mihalik
(greg23) - M

Locale: Colorado
Re: Re: Gravity filter vs. Aqua Mira: The age-old question on 06/20/2013 09:12:39 MDT Print View

By-the-Book for cold water is four hours. End of that discussion.
If you are going to accept less then that, you are talking about risk tolerance.

If you haven't seen it yet, here is Benjamin Tang's approach , third post down.

Gary Dunckel
(Zia-Grill-Guy) - MLife

Locale: Boulder
AM tablets vs. liquid on 06/20/2013 09:23:15 MDT Print View

"Aquamira tablets work much faster than drops."

That's an interesting statement, Nick. I discussed this with a pretty savvy employee at our local Jax store recently, and he also felt that the tablets worked faster than the drops, due to the effervescence as the tablets dissolved. So I contacted the Aqua Mira people at McNett, who told me that they both take the same amount of time. The pills take a few minutes to fully dissolve, about the same time as the AM takes to activate once you mix A and B. So could you tell us why you think the tablets are quicker?

(edit for spelling)

Edited by Zia-Grill-Guy on 06/20/2013 10:31:18 MDT.

Corbin Camp

Locale: Southeast
All depends on 06/20/2013 10:18:27 MDT Print View

Depends on where you are hiking I guess. I know there are plenty of zero treatment folks, but I know I'd rather carry the ~1/2 pound item I can use vs getting sick. I do think the amount of bad water in any wilderness is overstated, but I see that as safe than sorry type deal. There are plenty of places you can cut weight that have less affect on your health than some type of water treatment. I know I invest too much time and money into my trips to have them ruined because I wanted to avoid treating my water.

Ian B.

Locale: PNW
Re: Gravity filter vs. Aqua Mira: The age-old question on 06/20/2013 10:45:26 MDT Print View

There are a lot of variables that come into play. I know the tablets I have require four hours but many people are getting away with much less and not having any problems. Is this because:

1 The tablets are fully effective in much less time but AM is giving themselves room for error for liability reasons?
2 The water did not contain enough pathogens for the hiker to become symptomatic?
3 The hiker has immunity to the pathogens?
4 All of the above?

None of the systems are perfect but I love my steripen because it's fast and doesn't change the taste of the mountain water (which would be criminal imo). Since I'm hiking the Wonderland with my daughter this year, I've decided to bring the Sawyer as well as my Steripen to see if I develop a preference when using them side by side.

Jeffs Eleven
(WoodenWizard) - F

Locale: Greater Mt Tabor
Re: Re: Gravity filter vs. Aqua Mira: The age-old question on 06/20/2013 11:21:10 MDT Print View

From what I understand the 4 hour time comes from extremely cold water. ...Like near freezing water...

The protozoan cysts are tough and the hardest to break down. The cold water slows down the chemical reaction therefore you want to wait 4 hours to give it time to work.

As long as the water isnt super cold you'll only have to wait the 30 mins.

I don't see how tablets or drops could be faster than the other. Its the same chemical reactions, right? I'm no chemist, so... IDK

Edited by WoodenWizard on 06/20/2013 11:22:58 MDT.

Willie Evenstop
(redmonk) - F

Locale: Greater Yellowstone Ecosystem
Gravity filter vs. Aqua Mira: The age-old question on 06/20/2013 11:35:50 MDT Print View

Lett Appl Microbiol. 2011 Aug;53(2):225-30. doi: 10.1111/j.1472-765X.2011.03095.x. Epub 2011 Jun 17.
Chlorine dioxide inactivation of bacterial threat agents.
Shams AM, O'Connell H, Arduino MJ, Rose LJ.
Division of Healthcare Quality Promotion, National Center for Emerging and Zoonotic Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA.

Goal : To evaluate the efficacy of chlorine dioxide (ClO(2)) against seven species of bacterial threat agents in water.

Conclusion : To eliminate spores with chlorine dioxide at least 1Hour at 25C, and up to 7Hours at 4C

Jeffs Eleven
(WoodenWizard) - F

Locale: Greater Mt Tabor
Re: Gravity filter vs. Aqua Mira: The age-old question on 06/20/2013 11:40:45 MDT Print View

OK, so... an hour.


...I've never waited an hour... and water 'round here is definitely NOT 77F.

Here is a link to the Micropur tablet chart.

They state 30min for 20C water and 4hours for 4C water. Cameron's link (the 3rd party) differs greatly.

There must be a sweet spot in there somewhere... I wonder who B right?

Nicks statement below must be the answer. Tablets ARE stronger?!?!

Edited by WoodenWizard on 06/20/2013 11:54:04 MDT.

Nick Gatel
(ngatel) - MLife

Locale: Southern California
Re: AM tablets vs. liquid on 06/20/2013 11:44:23 MDT Print View

"That's an interesting statement, Nick."

Ben to World has done extensive research on this, but he hasn't posted in a while and is probably in some cool place on another continent. From what I remember, Ben has spoken to people at the factory, not users of the product.

Apparently the concentration is higher in the tablets and they have some sort of EPA approval for this, while the drops do not. Ben has posted extensively on this in the past, but I don't have the time right now to do a search.

Nick Gatel
(ngatel) - MLife

Locale: Southern California
Re: Gravity filter vs. Aqua Mira: The age-old question on 06/20/2013 11:55:19 MDT Print View

Here is my take on all of this and I have been backpacking since the 1960's. Also keep in mind that I often have to get water from desert seeps and springs where wild horses/burros and sheep probably contaminate water. I also have spent extensive time in the Sierras, San Jacintos, San Bernardinos, and Rocky Mountains.

If I think a water source is truly questionable due to location or via sight and smell, then it gets a full 4 hour treatment. If I have no water when refilling and need to drink right away, it gets boiled. I cannot rely on electronic devices or filters that may fail, because I am usually alone and cannot share with others. With a little route planning it is rare that I boil water, but I do at times.

To be honest, I don't fret about it.

I have never gotten sick because I am careful and probably lucky.

steven franchuk
Try the Sawyer in line sollution on 06/20/2013 12:37:35 MDT Print View

I tried tablets but found I wasn't always treating the water long enough. So I purchased the Sawyer in line filter. Basically you cut your blader hose near the bladder and insert the filters. So if your thirsty just suck on the bladder hose. Flow rate is sufficiently high that you can satisfy your thirst in a second or two.

My filter is called the Sawyer 3 in 1 (inline, gravity, straw filter). And connects to the blader hose with quick connect fittings. The newer Sawyer squeeze can also be used as an in line filter using optional screw on hose barb fittings. If you are already using a bladder it will only add the weight of the filter to your base weight and you will loose the weight for the gravity bag and hose. If I recall correctly my filter is only about 4 ounces.

Gary Dunckel
(Zia-Grill-Guy) - MLife

Locale: Boulder
Re: Gravity filter vs. Aqua Mira: The age-old question on 06/20/2013 12:39:35 MDT Print View

Here are the salient points of the reply from Aqua Mira:

1) It will take just as long to treat water using the drops as it will with the tablets.

2) When used as directed, both products will deliver approximately 4 ppm ClO2 in 1 liter of water.

3) Under a worst-case scenerio (really cold and turbid water), it takes up to 4 hours to neutralize cryptosporidium.

4) For quick access to drinking water, treat first with the drops or tablets, then filter.

Pete Staehling
(staehpj1) - F
Sawyer on 06/20/2013 12:47:06 MDT Print View

A couple things about your Sawyer comments...

1. The squeezing is pretty easy, but not even necessary.
2. It works fine as a gravity filter.
3. In my experience the bags, even the first ones, hold up fine if you don't squeeze them too hard.

Nick Gatel
(ngatel) - MLife

Locale: Southern California
Re: Sawyer on 06/20/2013 12:51:43 MDT Print View

What happens if the temp drops below freezing, which can happen 365 days of the year in the high Sierra?

Pete Staehling
(staehpj1) - F
Re Sawyer on 06/20/2013 13:32:33 MDT Print View

"What happens if the temp drops below freezing, which can happen 365 days of the year in the high Sierra?"

In my opinion probably nothing. It sounds to me as if damage is possible from freezing, but likelihood probably depends on how well it is shaken out and how cold it gets. I think it pretty likely that the filter would be fine after a freezing, enough so that I wouldn't freak out over it, but might replace it after the trip. That is just me and not based on any testing. Keeping it in a pocket during the day and in the sleeping bag at night is probably prudent and would remove the risk.

Colin Krusor
(ckrusor) - M

Locale: Northwest US
Others on 06/20/2013 14:24:59 MDT Print View

I have no desire to be alarmist, but I think it is important to note that Crypto and Giardia are the best known eukaryotic parasites in surface waters but not the only ones.

I study the protozoan parasite Toxoplasma. Toxoplasma oocysts cannot be killed by any chemicals that are safe to drink. After 24 hours in 6% bleach (twice the strength of the stuff in the bottle at a drug store) they are 100% viable and readily cause fatal infections in mice. In my lab, we store viable Toxo oocysts in sulfuric acid. Many human infections have been reported from ingestion of water contaminated with this parasite. In 1995, about 400 people in Victoria, BC became infected from municipal tap water (which was chlorinated). Subsequent research found that the source was toxoplasma-infected mountain lions living in the areas around the municipal reservoir. The parasites were being transported in the watershed. In some areas in California, the proportion of the mountain lion and bobcat population that has the infection approaches 80%. In humans, toxoplasmosis (like cryptosporidiosis) is typically a long-term subclinical infection following an initial bout of GI symptoms. However, it has also been implicated as a risk factor for schizophrenia and cognitive changes, and it is a serious risk to a fetus if a woman becomes infected while she is pregnant.

Cysts of eukaryotic parasites (worms and protozoans) are probably in all backcountry surface waters (excluding direct snowmelt) because they are shed in huge numbers by many wildlife species and (in contrast to bacteria and viruses) they accumulate because they are extremely tough and remain viable for months or years in water and soil. Polyparasitism (concurrent infection with multiple parasites) is certainly the norm in people in many developing countries now, and it was probably the norm among people in the US until about a century ago. On the American frontier, everyone probably had parasites, and people who continue to drink untreated water when backpacking probably have them as well.

In remote alpine areas with fast-moving streams (at the top of the watershed), the risk from pathogenic bacteria or viruses is minimal, so a large pore filter (like the Frontier Pro) is enough by itself, in my opinion. In areas lower down on a watershed, but still remote, a small pore filter (<0.3 microns) is probably adequate by itself (removes worm eggs, protozoa, and most bacteria). In lowland or coastal areas, or areas regularly used by other hikers or domestic animals, it seems to me that there are only three good options: boiling, steripen treatment, or a combination of filter+chemicals. In these higher-risk places, filters alone are risky because they don't remove viruses or small bacteria (ie, Lepto, Brachyspira, etc.), and chemical treatment alone is risky because it won't inactivate some protozoa.

I use a Sawyer Squeeze or a Sawyer gravity filter and carry Aquamira tabs. I can use the Sawyer alone in remote alpine places (and I have the Aquamira tabs in case the Sawyer freezes), and in lowland places I use both (and wait 30 minutes).

Alex Wallace
(FeetFirst) - F

Locale: Northern California
I've never filtered ice on 06/20/2013 14:39:05 MDT Print View

"What happens if the temp drops below freezing, which can happen 365 days of the year in the high Sierra?"

Is this a trick question?

I used the Sawyer Squeeze for all of my early season trips in the Sierra (6-9K ft) this year and would normally have freezing temps from about sundown to sunup. During these times the filter was placed in a Ziplock and stored in either my sleeping bag or in an article of clothing to keep it insulated from the cold.

When filtering in the morning, even though air temps are still at or below freezing, I was able to find running water from lake outlets or streams. Filter some unfrozen water, shake the filter to remove excess water, and place back into a warmer place in my pack.

If all I had a available was snow, then obviously I'd fire up the stove and start melting.

mark henley
(flash582) - F
Weight vs. time on 06/20/2013 14:40:09 MDT Print View

So, the question really becomes how much water do you need to have on hand when you reach the next water source. With a filter or UV device, the answer is zero. With chemicals you need to have a seperate reserve that will last until the required time expires for treating. This will vary based on ambient temperature, realative humidity, exertion levels, fitness levels, and your personal hydration requirements.

In temps between 40 and 60, with moderate exertion, humidity between 40 to 60 percent. conditions, I consume water at a rate of 1/3 liter per mile. In temps between 60 and 70 I increases to 1/2 liter per mile. 70 to 80 degrees increases to 1 liter per mile, 80 to 90 increases to 1 and a half liter per mile. 90 to 100 is 2 liters per mile .... Above 100 and I consume 1 beer per quarter of whatever sport is on TV at home on my couch.

This tells me the volume of water I need to carry to reach the next water source. At an average rate of 2 miles per hour, it also tells me how much I need to be carrying when I reach the next water source, to allow for perk time for chemicals.

Then compare the weight of your minimum water carry needs vs your filter/uv/other setup .. Carry the lighter option.

Pawel Carter
They really are all very good options - lucky us on 06/20/2013 14:57:12 MDT Print View

Aqua Mira - good; Sawyer Filter - good; Steripen - bad-deries (thinking of unloading my Adventurer). Seriously, aren't we fortunate to have so many good options? There is no right answer - it comes down to personality and environment. Try em all.

@ Mark - "In temps between ....80 to 90 increases to 1 and a half liter per mile. 90 to 100 is 2 liters per mile .... Above 100 and I consume 1 beer per quarter of whatever sport is on TV at home on my couch."

That's funny. That's also why baseball is America's game; 9 innings! Who needs quarters?