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Reviews > Water Treatment > Filters > Platypus Cleanstream Gravity Microfilter > Test Report by Nancy Griffith


INITIAL REPORT - May 31, 2009
FIELD REPORT - July 31, 2009
LONG TERM REPORT - October 02, 2009


NAME: Nancy Griffith
EMAIL: bkpkrgirlATyahooDOTcom
AGE: 43
LOCATION: Northern California, USA
HEIGHT: 5' 6" (1.68 m)
WEIGHT: 130 lb (59.00 kg)

My outdoor experience began in high school with involvement in a local canoeing/camping group called Canoe Trails. The culmination was a 10-day canoe voyage through the Quebec wilds. I've been backpacking since my college days in Pennsylvania. I have completed all of the Appalachian Trail in Georgia, Tennessee and North Carolina. My typical trip now is in the Sierra Nevada in California and is from a few days to a week-long. I carry a light to mid-weight load, use a tent, stove and hiking poles.


May 25, 2009


Photo courtesy of Platypus website

Manufacturer: Cascade Designs, Inc.
Year of Manufacture: 2009
Manufacturer's Website:
Listed Weight (on website): 388 g (13.7 oz)
Listed Weight (on box): 360 g (12.7 oz)
Measured Weight: 379.2 g (13.4 oz)
Listed Volume: 4 L (140 fl oz)
Measured Volume: 4 L (140 fl oz)
Listed Dimensions (on website): 3 in (8 cm) x 9.5 in (24 cm)
Listed Dimensions (on box): 16.5 x 9 in (42 x 23 cm)
Measured Dimensions (in storage sack): 3 in (8cm) x 9.5 in (24 cm)

Listed Flow Rate: 1.75 L (59 fl oz) per minute
Measured Flow Rate: 1.4 to 1.6 L (47 to 54 fl oz) per minute

Weight of individual parts:
Clean reservoir: 79.3 g (2.8 oz)
Dirty reservoir: 85.7 g (3.0 oz)
Filter: 113.2 g (4.0 oz)
Dirty hose: 16.4 g (0.6 oz)
Clean hose w/ shut-off clamp: 61.2 g (2.2 oz)
Storage bag: 23.6 g (0.8 oz)


Courtesy of Platypus Instruction Manual

The CleanStream is a water filtering system that uses gravity to pull water through a filter from a 'dirty' reservoir into a 'clean' reservoir. No pumping is needed.

The parts of the system include the dirty and clean reservoirs, the hollow fiber membrane (HFM) filter cartridge, dirty and clean silicone hoses, a shut-off clamp and a storage sack. There is also a cap for the clean side of the filter which can be used if the hose is not attached.

Both reservoirs have large nylon handles that can be used to hang the reservoirs and for ease when carrying water. Each reservoir has a zip lock type closure on the top.

The dirty reservoir has a female quick disconnect which attaches to a short section of hose with a male quick disconnect on one end. The other end of the dirty hose attaches to the inlet of the filter.

The filter has a black fitting to indicate the inlet from the dirty side and a white fitting to indicate the outlet to the clean side. There is also a large arrow on the side of the filter indicating the direction of flow.

The clean reservoir has a screw-cap type of attachment with the other end of the clean hose going to the outlet of the filter. The attachment to the reservoir can swivel 360 degrees.

There is a shut-off clamp included which slips over the hose. When snapped closed it prevents water flow. To open it I simply push down on the lower portion. It releases the clamp on the hose allowing water to flow.

The website claims that this product is effective against protozoa, bacteria and particulate but not against viruses, chemicals or toxins. The box states that it filters down to 0.2 micron, removes 99.9999% of bacteria and protozoa. Filter life is stated at 1,500 L (396 US gal) depending on water quality.

It is noted in several places that this filter is not intended for use in freezing conditions. There is a warning that freezing will permanently damage the internal fibers.


The system seems to be well-thought out so that there could be little chance of mistaking something on the dirty side as being clean or vice versa. The dirty and clean reservoirs are clearly indicated as such with 'DIRTY' and 'CLEAN' markings. Plus the connections to each are completely different so there appears to be little chance of me mixing them up. Also the black and white hose fittings on the filter make it very clear how to attach them appropriately.

My first reaction was how light the entire system seemed. Without weighing them, it seemed that it was similar to my current water filter pump. After weighing them, I found that my filter pump is actually slightly heavier than the entire CleanStream system. Granted my pump has been used, so I may be weighing some gunk in the filter too.


The instruction manual came in a packet with 9 separate manuals in various languages. It is clearly written and contains 5 sections of information: how to assemble the system, filter water, backflush the filter, pack/store everything and disinfect the filter. There are diagrams included with each section.

There was also a multi-language insert with instructions for how to test the filter. The filter test consists of backflushing some water from the clean reservoir into the dirty reservoir and then blowing into the clean tube. If bubbles blow through the filter then the fiber is broken and the cartridge needs to be replaced. If air cannot be blown through the filter then it is ok.


The first thing that I did upon removing the system from the box was to assemble it. The assembly was completely logical but I looked at the instructions just to make sure. The hoses fit easily onto the filter fittings. The quick connect on the dirty reservoir was easy to operate and seemed to provide a secure connection. The screw attachment to the clean reservoir was easy to connect.

Since I wanted to weigh the system without the influence of any added water, I did not immediately try out the filter. Instead I skipped to the packing and storage section. The instructions say to lay the reservoirs on top of each other, wrap the hoses around the filter, roll it all up and place in the storage sack. I did this and it worked fine. I was able to fit it in the storage sack with slight difficulty. I then just rolled the filter up with the hoses folded inside and not wrapped around the filter. This way I was able to put the system in the storage sack with ease.

After weighing everything, I proceeded with checking out the filtering. I first measured the water with a measuring cup as I filled the dirty reservoir. There are graduation marks at 1, 2, 3 and 4 L (34, 70, 100 and 140 fl oz). I found them to be fairly accurate and could not fit more water over the 4 L (140 fl oz) line and still be able to close the top. Then I hung the dirty reservoir above the clean reservoir and timed how long it took to filter 4 L (140 fl oz) of water. In 2 minutes 52 seconds, the clean side was full to the 4 L line and the dirty side was empty. I repeated it with fresh tap water twice and on the second repeat it was not flowing correctly.

I backflushed the filter by hanging the clean reservoir above the dirty reservoir. Then I repeated the timed filtering test three times using the same water and backflushing all of the water between tests. It took 2 minutes 48 seconds, 2 minutes 28 seconds and 2 minutes 43 seconds to filter 4 L (140 fl oz) of water. The box claims that it takes 2 minutes 30 seconds, so my results were fairly close to that but slightly longer. Even if it isn't exactly as fast as claimed, the water flows so quickly that I can see the water line moving rapidly. It is really amazing to me how fast this filter works and I don't even have to pump anything.

Lastly I followed the instruction on the insert to check the filter. I backflushed a little water into the dirty side, disconnected the clean hose from the clean reservoir and blew air into it. I was not able to blow any air through the filter thus concluding that it is intact.

During my kitchen testing, I filled the reservoir with a measuring cup or directly from the tap, but I am interested in how easy it will be to fill on the trail. I am wondering if it will be easy to fill in a flowing stream and in a lake just by dunking it or whether I'll have to use a pot to pour into it.

Pouring water from the top of the reservoir is awkward and does not flow neatly. This is clearly not the preferred method, but it is easy to pour from the lower coupling on the clean reservoir.

Since I am a big fan of using my gear in multiple ways, I was interested in whether the clean reservoir could also be used as a hydration bladder. The zip lock closure on the clean reservoir seems secure enough for in camp but when a lot of pressure is applied like it would see in my pack sleeve, it opens. I plan to further investigate this during my test period.

The reservoir material seems to shed water and the zip lock top tends to stay opened slightly when unzipped. So, I found it very easy to dry the reservoirs.


From my initial look at the Platypus CleanStream system I am very satisfied. The system seems to be well thought-out, of high quality construction and very efficient. My favorite feature is its light weight even as a complete unit. Plus, I can envision that on trips where I really want to travel light that I could not even carry the clean reservoir and clean tubing. I'll definitely carry and use the complete system during the test period, but I also plan to test it with these options in mind.

Initial Likes:
Rapid rate of filtering
Light weight
Ease of drying

Initial Questions:
How frequently will I need to backflush to keep it operating smoothly?
Will I have to use another pot to fill the dirty reservoir on the trail?
Is there any way to use the clean reservoir as my hydration bladder?



I used the Platypus CleanStream gravity filter for 7 days of backpacking and 3 days of boat camping. For boat camping, we take our small fishing boat to a remote section of a mountain lake and camp on the shore. Including my time trials at home, I have filtered 86 liters of water so far.

Hunters Trail, Sierra Nevada (California): 3 days; 20 mi (32 km); 3,500 to 5,000 ft (1,067 to 1,524 m); 48 to 70 F (9 to 21 C); filled dirty reservoir 3.5 times (14 L). One water source was a slow section of river and had a little algae in it. The other was a nice pool section of the same river.

Pacific Crest Trail, Sierra Nevada (California): 4 days; 29 mi (47 km); 7,820 to 9,000 ft (2,384 to 2,743 m); 45 to 75 F (7 to 24 C); filled dirty reservoir 9 times (36 L). Three of the four water sources were flowing streams of mainly snowmelt and one was a small lake.

Boat Camping:
Loon Lake, Sierra Nevada (California): 3 days; 6,200 ft (1,890 m); 50 to 75 F (10 to 24 C); filled dirty reservoir 3 times using lake water (12 L).


The main thing that I notice (and love) is the lack of effort required to use this system. I simply detach the hose from the dirty reservoir, fill it and hang it in camp. Then I attach the filter and clean hoses and I'm free to do other things (or nothing at all) while the water filters.

The reservoir was easy to fill without using another container to scoop water and pour into it. In the streams, I simply held one of the top handles and allowed the water to flow inside (at times while hanging on tightly in the fast run-off!). In the lakes, I could again hold one handle and then swing the reservoir into the water a few times to fill it. As some water got inside, that water helped to keep the reservoir under water allowing it to fill completely.

When there were appropriate trees around, I hung the dirty reservoir on a higher branch and the clean reservoir on a lower branch. I found that carabiners helped with this since the branches rarely were just stubs that the handles could slip over. At times there were no appropriate trees at all. So, in this case, I just laid the dirty reservoir on a boulder higher than the clean reservoir. In this case both reservoirs had to be securely closed at the top to keep the water from accidentally flowing out.

The top zipper seal on either reservoir is difficult to secure. It is especially difficult to secure the one on the dirty reservoir when it is full of water. At times I didn't bother and just tried to be sure that nothing dropped into the reservoir. I did make sure that the clean reservoir was closed (to keep it clean). This area could use a new closure method. The insecurity of the closure also keeps the clean reservoir from being used as a hydration bladder. I haven't yet filtered directly into my hydration bladder simply because it doesn't hold 4 liters, so I would have to remain vigilant lest it overflow. I do plan to give it a try during the Long Term test period.

Although there is no pre-filter, I only had a few instances of something getting into the filter. Once there was an ant in the tube (that I hadn't seen) and it got sucked in. Another time a small stick got sucked in. Since the outlet at the bottom of the dirty reservoir is slightly above the very bottom, it allows silt and other heavier things to settle in the bottom without getting sucked out into the filter. In the case of the ant and stick, I simply backflushed the filter to get them out.

The stuff sack was easy to use. I had no problem rolling up the filter and hoses inside the two reservoirs and fitting it all into the sack. It comes out easily too. The remaining water in the reservoirs and hoses didn't cause any problem with leaking onto my other pack items. If anything, a few drops of water came out, but I never noticed any moisture in my pack.

My maintenance routine after each trip was to disconnect everything, rinse thoroughly and allow to dry before packing it away. I occasionally backflushed the filter and typically removed the dirty reservoir when I did. This way anything that flushed out of the filter would just go onto the ground rather than into the reservoir to get sucked back through the filter. I never really saw anything of any significance come out of the filter.

The reservoirs seem durable. There were many occasions where I had them lying on granite and at times had to lie them on the rocks to filter when there weren't any appropriate tree branches for hanging them. However, there is no sign of abrasion or wear. The handles, hoses and filter show no sign of wear at all. The hose attachment points work as well as when I received the system. The attachment on the dirty reservoir connects and disconnects very easily.

It is difficult to assess the effectiveness of a filter to screen out bacteria or other nasties in water. We always try to use the cleanest water source available. On one night I had a stomach illness but I cannot attribute it to bad water. My husband also drank the same water and had no problems.

The CleanStream system was a hit with our backpacking friends. They were envious of our lounging around camp claiming that we were busy filtering water. We did share our water with them though and they ended up buying their own CleanStream when they got home. We also filtered water for a Pacific Crest Trail thru-hiker who wasn't carrying a filter...brave (naive) soul.

I repeated my time trials for filtering 4 L of water at the end of this test period to see how much it had slowed. I had noticed a definite slowing but since I never was in a big hurry, it didn't cause any problem. I was a little concerned about how soon it would be before it slowed to a stop. The results of the time trial were:
1st filtering of 4L tap water: 5 minutes 10 seconds
Backflush (of all 4 L): 19 minutes 8 seconds
Re-filtering of same 4 L: 4 minutes 29 seconds

These filtering times are nearly double what they were when the filter was brand new. I hadn't timed the backflushing time as new, but I know that it wasn't nearly this long.

I wish that there were some feature to give an indication of how much filter life is left. With my old pump filter, I could unscrew the filter and see exactly how grungy it looked. With the CleanStream I can only base it on how slow the filtering becomes or how many liters I've filtered with it. The filter life is listed at 1,500 L which means I've only used a fraction of it. However, since the filtering time has slowed so much, it concerns me. I don't want to carry an extra filter for no reason, but I'll have to at some point.


Gravity is a fabulous way to filter water!

Things I like:
Ease of use
Large volume (4L)
Ease of cleaning/drying the reservoirs
Shut-off clip

Things I dislike:
Can't tell when the filter needs replacement
Slowing of filtering time after only 86 L



During the long-term testing period, I used the filter for 8 days of backpacking and 5 days of camping for a total of 13 days and 60 liters. The water sources are listed below for each trip. All of the sources were fairly clear water with no visible signs of dirt or contamination.

Filling in Pond
Pacific Crest/Tahoe Rim Trail, Northern Sierra Nevada (California): 3 days; 7,390 to 9,010 ft (2,252 to 2,746 m); 50 to 85 F (10 to 29 C). I filled the reservoir 2 times (8 L) from a slower flowing creek using a pot to scoop the water first. Filled 2 times (8 L) with water flowing from a lake outlet just by holding the reservoir under the flow.

Appalachian Trail, White Mountains (New Hampshire): 3 days; 2,032 to 5,367 ft (619 to 1,636 m); 45 to 70 F (7 to 21 C). I filled the reservoir 3 times (12 L) from a slow flowing spring and one time (4L) in an alpine pond.

Pacific Crest Trail, Central Sierra Nevada (California): 2 days; 9,610 to 10,500 ft (2,929 to 3,200 m); 40 to 70 F (4 to 21 C). I filled the reservoir 1 time (4 L) from a late season flowing creeklet using a pot to scoop the water.

Baxter State Park, Maine: 4 days; 1,079 ft (329 m); 38 to 65 F (3 to 18 C). I filled the reservoir 5 times (20 L) in clear fast-flowing Katahdin Stream.

Shawme-Crowell State Park, Cape Cod, Massachusetts: 1 night; nearly sea level; 40 to 55 F (4 to 13 C). I filled the reservoir once with campground tap water.


Water Ready!
Water Ready!

I love having a ready supply of clean water in camp. We simply fill the dirty reservoir upon arrival in camp and soon have 4L of water ready to use for washing dishes, cooking or drinking. After filtering, I detach the dirty side and leave the clean side hanging with the shut-off clamp on its hose. Then I simply open the clamp to get clean running water.

The filtering time has been slowing and air bubbles definitely cause a problem. At times the dirty water level seems to not be changing and I have to hit the tubing several times to knock out any air bubbles. Once it gets going, it has had no problem finishing. The amount of slowing of filtering time is a definite concern to me. The filter life is listed as 1500L but I have only filtered a few hundred liters and have seen a large increase in filtering time.

I again repeated my kitchen time trials for filtering 4L of water at the end of this test period. The results of the time trial were:
1st filtering of 4L tap water: 9 minutes 37 seconds
Backflush (of all 4 L): 3 minutes 32 seconds
Re-filtering of same 4 L: 4 minutes 2 seconds
This is quite a bit longer than filtering time I measured during my Initial Report, (2 minutes 48 seconds to 2 minutes 28 seconds).

I haven't used the filter on trips where the temperatures dropped below freezing. On our last backpacking trip, I was concerned that it could drop below freezing, so I put the filter in the tent overnight. I plan to wrap it in some clothing and leave it in the tent overnight on any nights that could possibly drop below freezing.

The top seal closure of the clean reservoir continues to be difficult to close. This test period saw some lower temperatures and I found that at temperatures below 50 F (10 C) it was simply impossible for me to close it. I spent about 15 minutes in morning temperatures of 48 F (9C) experimenting with various methods to close the seal. I finally gave up. My husband (who has MUCH stronger hands than I) also had difficulty. This wasn't a big problem since we learned to close the clean reservoir seal at home and never open it on the trail. We only opened it for cleaning at home. The dirty reservoir was often left open and we tried to keep debris from falling it. On our last trip, however, it was a problem to not close the dirty reservoir. The water collection point was several steps up a small creeklet surrounded by willows. As it is now autumn, the leaves were falling readily. While trying to squeeze between the willows with a full dirty reservoir, leaves would fall into the water. The force of the full water was also pushing open the seal. We ended up squeezing out quite a bit of water and managing to keep the seal closed just long enough to take those few steps.

There haven't been any issues with durability. The reservoirs are perfectly intact despite a lot of contact with granite and tree branches. The handles are securely attached and have not frayed or loosened. The hose connections are working as well as when it was new.

I always found it easy to roll up and store the system in the storage bag. I didn't use the exact same technique every time, but I never had to struggle with fitting everything into the bag. The fit is not at all sloppy though. It is just right.

I wasn't able to filter directly into my Polarpak hydration reservoir because it has tubing which is too stiff to easily remove from the fittings. I was able to do it with my Camelbak. It works fine but since it has a smaller volume, I have to keep an eye on it. I prefer to just let it filter into the clean reservoir and use the water from there.

I originally was interested in whether the clean reservoir could be used as my hydration bladder thus allowing me to drop a piece of gear. Due to it not having a secure seal, it cannot. Then I wondered if I could just leave the clean reservoir at home and filter directly into my hydration bladder, pot, etc. While this could be done, I could not do it with my current hydration bladder (as mentioned above), would have to backflush using my hydration bladder and would not have as ready a supply of water since it would have to filter first. So, I find it more worthwhile to carry the clean reservoir than to save a few ounces and deal with the other inconveniences of not having it.


I love using gravity to filter water and love having a source of clean running water in camp. It was especially handy when used with a group. I'm less enthused about the filtering time lengthening, the lack of ability to monitor the filter and the difficulty closing the top seals. Overall though the pros outweigh the cons for me.

Things I like:
Ease of use, i.e. NO pumping
Large volume (4L)
Ease of cleaning/drying the reservoirs
Shut-off clip
Ease of fit in storage bag

Things I dislike:
Increase in filtering time
No way to monitor the need for a filter replacement
Can't open filter for rinsing or drying
Difficulty closing the reservoirs

This concludes my Long-Term Report and this test series.

Many thanks to Cascade Designs and for allowing me to participate in this test.

This report was created with the Report Writer Version 1.5 Copyright 2009. All rights reserved.

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