David,

Humm....to be honest, I have never timed the flow rate.

I can tell you that when I use the filter with the pint bottle, I can "suck" water through the filter about half as fast as I would if I was using a straw.

Essentially, I have not felt like I was delayed in getting water on the trail using the method above.

Using it as a gravity filter, I think that I have been able to fill up my 1.8 L Platypus Hoser in 2 or 3 minutes?

To be honest, since I have used it as a gravity filter in camp, I have been running around doing other things while the filter has been doing its thing....so speed was not too important to me.

Speed of the gravity filter is going to be determined by the clarity of the water (is there a lot of particles/dirts/debris in the water that you are filtering) and the length of tubing that is used between the dirty water bag and the tubing from the filter to the clean bag.

I don't know the scientific reasons for this, but the longer the tube the more suction might be created which speeds up the rate of flow...so this is a variable in the speed or rate of flow.

I agree, if someone is testing the Clean Stream, you would have a predictable rate of flow because the system is uniform.

Making your own gravity filter creates a variable in tubing length = increase or decrease of rate of flow from a known standard, such as the Clean Stream system.

Anyway, another way to speed things up....sit on the dirty water bag, which increases pressure and speeds up the process.

I am so lazy now that I just lay my dirty water bag on a fallen tree or rock and let gravity do its thing....as long as my clean bag and filter are pointing down hill, gravity works.

Okay, as for the taste, the Sawyer filter does absolutely nothing to improve the taste of the water.

There is no active charcoal in it.

If the water taste like crap to start out with then it is going to taste like crap on the way out...you just don't have to worry about bacteria making you sick.

-Tony

P.S. If I get a chance tonight, I will take some photos of the inside of the Sawyer filter to show people what is in there. Photos would be posted to my reader review. The new ones are glued shut. Sawyer was saying that people were opening them up and poking around inside and damaging the filtering tubes.

Edited by Valshar on 06/08/2009 16:23:32 MDT.

I use the sip-and-go method when hiking and a drip system when in camp. The drip system is similar to yours (one clean platypus, one dirty one). I don't treat before filtering. I used to use a Seychelle, but recently ordered a Sawyer. The Sawyer is noticeably slower. I may go back to the Seychelle.

In general, though, the approach is as fast as pumping (if not faster, since you have to deal with fewer hoses) and very light (since you carry no water if you are in a place with lots of water).

Ross,

Do you have any quantitative results comparing the Seychelle vs. the Sawyer? How do they compare in terms of technology (i.e., how good are they in terms of filtering out baddies)?

Tony,

Yeah, I'd like to see some pics and also some more testing results on the filter rate.

All,

I think I'm just gonna have to buy the dang Sawyer and Platy Clean Stream system and do some testing on my own.

David

David,

I just uploaded a series of photos showing the dis assembly of the filter to show what the inside of the filter looks like and a few observations about what might make some difference between the rate of flow between Sawyer Filters.

Photos are in the User Review Section for Water Filters, Sawyer In Line Filter:

http://www.backpackinglight.com/cgi-bin/backpackinglight/reviews/display_reviews?forum_thread_id=5536&cat=Hydration%20-%20Water%20Treatment&cid=55

-Tony

Tony

Thanks for the pics.

I am curious how Sawyer substantiates their 1 million gallon guarantee. How can they be sure that contaminants are being trapped during those million gallons?

Also, can/must the filter be backflushed in the field to maintain cleanliness? I read somewhere that the Sawyer FILTER (0.2 micron?) can and should be backflushed, while the Sawyer PURIFIER (0.01 micron?) must be backflushed under high pressure, such as your faucet at home.

The Platy Clean Stream system uses backflushing to maintain cleanliness. Since both the Sawyer and Platy seem to utilize the same hollow-fiber technology, you would think that both would operate the same way.

Finally, why do I keep hearing that the Platy Clean Stream filter keeps clogging? Were these early production samples, or has Platy improved? Need to hear more feedback on this.

Thanks.

David,
Sorry, I don't know the various numbers. If someone has them, this would be good data for the wiki. I'm pretty sure the Sawyer filters out more than the Seychelle. I'm pretty sure the Seychelle does not handle viruses. However, since I stick to the northern areas, I feel pretty safe. I would use a different filter (or boil) if I went to the third world.

David,

Good questions, unfortunately, I don't have good answers for you.

The longest that I have used the Sawyer filter in the field is 4 days with very clean/clear water sources.

As a habit, when I get home I back flush my filter using a faucet/hose attachment to create a high pressure back wash to clear any debris out of the filter.

Since mine is not sealed, I have opened it up to see/find particles inside that were trapped.

Following Sawyer's instructions, I also mix about 10 drops of bleach into a Liter of water and run it through the filter to kill off anything that might be in there.

As the hollow tubes are synthetic, I doubt that anything is going to grow in there, but I am a bit anal about stuff so I clean everything.

I think that the million gallon guarantee is their way of saying life time guarantee.

I am guessing that if the filter were to clog due to silt or "stuff", since the pressure used to clog the hollow tubes is relatively low, the pressure needed to back wash/flush the filter is equally low.

I haven't needed to backflush my filter in the field, but it would stand to reason that I would simply turn the gravity filter system "upside down" and force clean water through the filter....for added pressure, I would squeeze or sit on the clean water bag to increase the pressure of the water to help blow out any particles that would have clogged the filter.

Fortunately or unfortunately, I have not tested the filter out by filtering a mud puddle. :)

Best we can hope for is to get some field reports from other users.

P.S. I agree with you that the Clean Stream and Sawyer use the same technology. I have not used the Purifier version of the Sawyer filter, but it does sound like a faucet would be needed to backwash that one.
-Tony

David,

I just tested my sawyer's flow rate and it passes through 1 liter of water in 1 & 1/2 minutes.I've got a simple platy bladder->hose->sawyer->hose set up.

On my last hike in the Sierras my group's pump filter failed. I was using my Sawyer inline for personal use but it soon became the only filter for a group of three. It handled all our drinking needs for the last 2 days of our hike very well. I never felt like it was taking any longer for me to get water than when using a pump. And of course, no work. Just fill, and let drain.

Ian David

Ian,

Thanks for doing that test and getting the results back to us.

Can you tell me how many inches of tubing you have between the filter on the clean and dirty sides?

My understanding is that the longer the tubing, the faster the rate of flow/filtering.

-Tony

Tony,

From my experimenting with the Frontier Pro, I can assure you that tubing length makes a big difference BETWEEN THE DIRTY BLADDER AND THE FILTER. You see, Pressure = Force / Area. Force is equivalent to the gravitational force on an object, in this case it amounts to the weight of the water. The more water you have in the tube above the filter, the faster the flow rate. As to whether it matters if you have long or short tubing between the filter and the CLEAN bladder, I don't think it would matter. In any case, I use a Platy hydration system with a drink hose, so my drink hose becomes my connecting tube.

BTW, you mention using "food grade vinyl tubing" in your Sawyer review. What type of tubing did you buy exactly and where? Do you find that this tubing is lighter than the standard Platy tubing? The Platy tubing seems rather heavy.

Ian,

Do you feel confident that your filter is trapping contaminants? Does it ever clog or slow in rate when it has been used alot? Do you backwash it in the field to maintain filter integrity?

Edited by dgposton on 06/09/2009 14:04:56 MDT.

Really, how?

David,

The food grade tubing that I was refering to was from Home Depot, which I ended up not using. I just wanted to point out in my instructions that you want food grade tubing vs. something else that might leach chemicals into the water.

The food grade tubing might have been lighter, but my recollection was that the tubing was not very flexible.

With the system that I have now, I simply used the short tubing that came with the Sawyer filter to build my connection between the Filter Link and the Sawyer Filter.

Small note, if you see my photo of the filter, on the output end, I have a short two inch section of tubing.

I don't use that for connecting to my Platypus Hydration System and it really is not necessary for using it with the pint bottle.

If I hang my gravity filter from a tree I plug in my Camelback bite piece to that small 2 inch section of tubing so that when I am doing filtering, I can let the bag hang and the bite valve prevents any loss of water.

Futhermore, it becomes a faucet....I put my mug under it and just squeeze the bite piece and the water starts flowing.

I don't do this often, but in a larger group setting with a 4 L Platypus, it allows multiple people to share the water without having to take down and then re-hang the setup when I want more water.

-Tony

"Can you tell me how many inches of tubing you have between the filter on the clean and dirty sides? - Tony"

Tony,

I think I've got about a foot and a half of tubing on either side of my sawyer.Longer tubing is heavier than a short piece but, like you said it may influence flow rate. Also, it increases the number of suitable spots you can set your gravity filter up on. Basically I took the Platy drink tube, cut it in half, and stuck the filter in. I have no idea if this is optimal location for the filter but it works very well.



"Do you feel confident that your filter is trapping contaminants? Does it ever clog or slow in rate when it has been used alot? Do you backwash it in the field to maintain filter integrity? - David"

David,
I guess it would depend on what you mean by contaminants. Like others have said, the Sawyer has no charcoal component and doesn't seem to really improve the flavor of the water, so I doubt it does anything to remove chemicals etc. That said, I've never gotten sick using the system and I certainly feel 'confident' using it.
The filter does seem to slow a little with use but not much. I am always very careful to select the cleanest, clearest water possible. I almost never take water from mucky lake shores or anywhere there is lots of fine silt and sediment. When It seems like the filter might benefit from a backflushing I've discovered that a hydration syringe does a great job. I know this is not an item most light weight hikers carry into the back country but, after taking a NOLS Wilderness First Responder course there are three things that always go in my med kit no matter how light I'm going.

1. Ibuprofen
2. Athletic Tape
3. Irrigation Syringe

An irrigation syringe is fantastic for flushing out nasty ragged wounds (a common injury in the backcountry where we all interact with rocks, sticks & dirt) There is no sharp needle on it, it just shoots water at a good pressure. Mine fits onto the outlet of my filter pretty well and I just squirt several shots of clean water through it when I want to clean it out. Works great. Usually though, on anything but a very long trip or one where the water quality is very low, it hasn't seemed imperative to back flush the unit in the field.


Cheers,
Ian David

Ian,

Thanks for the info there...I carry a small irrigation syringe too....never thought of using it to backflush.

Thanks for the tip!

David,

Having opened up my filter at home and flushing it out, I have seen the larger particles come out of the filter.

Basically, the hollow tube have small holes/pores that allow the water to pass through and everything else is trapped on the outside of the hollow tube walls.

So if the filter is going to clog up, we are talking about particles that are 0.2 microns small to plug up the pores in the tubes.

Bottom line is that someone needs to filter some mud water and give us some results back.

-Tony

I finally decided to head over to Wal-Mart to resolve my curiosity. I found this for $40:

http://www.walmart.com/catalog/product.do?product_id=8283710

The filter unit itself appears to be identical to the one that REI sells for $45. However, the one at REI says, "1 million gallons guaranteed," while the Wal-Mart version says, "up to 500 gallons of bacteria free water." What gives? They are both 0.1 micron filters. I've inspected both firsthand. They are exactly the same.

In any case, I did a bit of testing tonight in my backyard. I ran 4 L of tap water through the filter using Platy tubing about 29.5" long between the dirty bag and the filter. Filter rate was quite good, about 5 minutes for the whole 4 L. I tried filter less quantities at a time (say 2 L), and the rate wasn't as good but still not bad. About 3-4 minutes for 2 L.

If the rate of filtration in the field matches that in my home, I think we have a winner here. The filter system, inclusive of the filter unit, the dirty tubing, and a 2" length of clean tubing attached to a male-male nipple (to attach to your clean hydration tubing) weighs in around 4.1 oz when wet. Not bad. Add about 3 oz for a dirty bladder and 0.3 oz for a cheap water bottle scoop for dirty water, and you have a system under 7.5 oz, not counting your clean hydration system. My current system in use is an MSR Sweetwater which weighs in at 11 oz and doesn't come with a dirty/camp bag, which I always end up bringing along anyway to haul water to camp for cooking/cleaning. I guess bottom line is that I am looking at a 6.5 - 7.0 oz weight savings and have to decide whether or not it is worth the hassle of setting up the gravity system. (Since I travel with my wife mostly and thus split the weight of our items, the extra weight of the Sweetwater pump system may well be worth the convenience).

David,


Just interested in your thinking here.

"I guess bottom line is that I am looking at a 6.5 - 7.0 oz weight savings and have to decide whether or not it is worth the hassle of setting up the gravity system."

How is it more convenient to pump than to let gravity do it? Even if you can't find a place to hang it or set it on a big rock (which has never happened to me) you can always just hold the dirty water bag in your hands while your standing up. It's definitely not more work to hold it than to pump. As far as the speed of the system goes, I don't think I've ever gotten a pump to do much better than a litter in a minute or two. I'd be interested to know how fast it takes to pump a liter of water with your sweetwater.

Ian

David, the disadvantage of the Walmart Sawyer filter bottle is that it doesn't come with the fittings for backflushing with a faucett.
https://docforgey2.com/products.asp
is the same thing except comes with the backflushing connections. I think REIs comes with the extras also.

What baffles me about the Sawyer filter is the ambiguity regarding backflushing. The instructions have an advisory that says something to the effect, "Do not reverse the flow of the water." Do they mean, "Do not run dirty water in a reverse direction," or do they mean not to backflush clean water through the filter. Certainly, they can't mean the latter, because they mention using the faucet adapter to backflush. However, my question is this: Can/should you backflush it in the field (like the Platy Clean Stream instructs), or should you wait until you get home to your faucet?

Also, is there a test you can do to make sure the filter is working properly? On the instructions for the Platy Clean Stream, it says to try to blow bubbles through the filter in a backwards direction. I tried this on the Sawyer, and air seemed to pass through in the reverse direction. Is this bad?

***************

Ian David,

Regarding your question about the convenience of the Sweetwater pump system vs. the Sawyer gravity system, I guess it comes down to two variables: a) flow rate and b) prep time.

Let's discuss these two variables in turn.

a) The flow rate of the Sawyer seems good now with tap water, but I don't know what it would be like after 1 month of thru-hiking. Also, the ambiguity surrounding whether you can backflush in the field exacerbates this. Is backflushing in the field OK? Will it improve the flow rate of the filter back to original specs?

The flow rate of the MSR Sweetwater, on the other hand, is not contingent on the filter itself but on my own muscle. If it slows, I pump harder. Also, it is field-cleanable with the brush provided.

b) The prep time is undoubtedly longer for the gravity setup. Filling your dirty bag will take time. Even a 4L Platy water bag with a zipped top will only accomodate about 2L maximum before you have to top it off with another scoop container (don't forget to factor that into the weight of your system). If the water source is really shallow, you will have to scoop and pour most of the water. If you have a deep pool or a running stream, this will probably reduce your prep time. You also have to find a place to hang your bag, which involves rigging some cord for this purpose. Sure, you could stand and hold it, but you would have to stand pretty high to accomodate the 30" length of dirty tubing between the dirty bag and filter and then some to accomodate the clean tubing.

With the pump system, you just place your dirty tubing in the water and pump away. Even shallow streams can be pumped successfully.

Last but not least, the Sweetwater has a carbon element to improve taste.

I think will do some experimenting in my backyard and time the prep-time as well as the flow-time for both filters. I will place water in a bucket-like container to mimic a water source. Then I'll come back with some data.

Edited by dgposton on 06/10/2009 14:25:50 MDT.

David,

I completely agree about the ambiguity of the Sawyer's back flushing instructions. They are very poorly written to be sure. I have always interpreted them as to mean "don't try to drink water through the device the wrong way" which would of course result in drinking some contaminated water.

As far as backflushing in the field goes, I can think of two ways it can be be done with about as much effort as cleaning out a pump. But, only if you have the appropriate equipment at your disposal.

1. If you have a water tight connection between your clean reservoir and your filter you can just press down on you full, clean reservoir and push some clean water through the other way. Very easy to do if you have this kind of set up.

2. If you don't have a water tight connection between your clean reservoir and the filter you can use a hydration syringe like I suggested earlier in this thread. A down side of using an irrigation syringe is that it would certainly take longer to use the syringe than a faucet adapter.

With that said, I must concede that I don't know how well the Sawyer would hold up on a month long through hike and I think it is a legitimate concern. I've used a Sawyer in the field on about half a dozen trips and never experienced a significant reduction in flow. However, like I said before I take great pains to choose clean, clear water and the trips I've used the Sawyer on have all been between three and five days, far short of your proposed month.

I imagine if you tried to filter a bunch of mucky or silty water through a sawyer you 'could' reduce the flow pretty substantially. Could you clean it out to O.G. flow rate in the field? Don't know.

As far as the prep time goes, I'll just make a couple of last words, as ultimately this comes down to personal preference.

I would estimate that it takes me some where around five or six seconds to 'completely fill' and close my platy big zip in any stream deeper than about a foot, and maybe another five seconds to put it down on a big rock to let it drain. I also think that it would be significantly more of a pain in the *ss to fill a big zip from dunking it in a bucket than scooping it horizontally through a stream (the scoop method is the key!)

Any way, I appreciate this discussion, thanks for bringing it up.

Ian David

Has anybody had any experience with the Triton inline water filter/purifies?
I have purchased the filter but haven't had a chance to use it yet. The filter weights just a smidgen over 4 oz. and has a charcoal media and stainless pre-filter built into the unit. You can also add a viral module to it as well, but not sure how much that adds to the total weight. It is also a little bulky but otherwise looks like a solid unit. I hope it does the trick clean and fast...