“Oh man, you just turned our campsite into an ER!”
The CleanStream is a gravity filtration system that resembles an IV bag. Consisting of two Platypus bladders, two hoses, and one 0.2-micron-thick hollow fiber filter (w/a cartridge that’s good for ~1500L), this $90 system can handle bacteria, protozoa, viruses and particulate &mdash i.e. the gunky yellow stuff that came out of the spigot at our campsite (see below).
The CleanStream is straightforward to use. After attaching the hoses to either end of the filter, you fill the “dirty” bag from your stream, spigot or other source (avoid shallow, still puddles!), and hang up the dirty bag, leaving the “clean” bag on the ground or somewhere below the dirty one. Instantly, gravity pulls the H2O down through the filter and into the “clean” bag. There’s also a clip on the hose that lets you pause the filtering if, say, you need only a smaller quantity of water in one minute vs. three.
I will admit the spigot where we were camped was unlikely to have any contaminants, bacteria, etc. However, there’s something about drinking yellow water that doesn’t sit too well with me. Thus, we double-filtered our water, which dramatically reduced the yellow:
[Note: to avoid mixing up the bags during use, write "dirty" or "X" on the dirty bag with a Sharpie.]
Gravity filters aren’t new, but this was my first time trying one out*. Reason being the $90 price tag makes it somewhat of a luxury item, imho. When I backpacked Hawaii for 2 months in college all I used were $7 for iodine tablets. I drank from streams and waterfalls and never got sick, but the taste wasn’t terrific and using tablets required way too much time: drop in tablets, wait 30 minutes, and then another 30 minutes if you also use the taste-neutralizing tablets (which I did not).
At the time, though, the tablets were way more preferable to filtering with a hand-pump. After hiking 12 miles of rocky coastline, the last thing you want to do is expend energy just for a sip of fresh water. If you’re car camping (which I was recently), you’re likely partial to gear that will make the experience as cush and convenient as possible.
So for $90, you can have potable water in less than 3 minutes, literally, by doing nothing. Or you could spend $7 to have potable water in 30 minutes. Or you can spend somewhere in between on a hand-pump filter and get some added exercise. Your call.
*It’s worth noting there are other systems some packers have been using in conjunction with Platypus bladders, including the Sawyer and Aquamira Frontier Pro. I have no personal experience with either.



The note about using a Sharpie to label the bags seems odd, given that one bag is already labeled “Clean” and the other “Dirty”.
Two words: chlorine dioxide.
Also commonly called by the brand name “aquamira”. Think of it as a tasteless, odorless iodine. Still have to wait the 30 minutes, but very lightweight, cheap and effective. I used it for 6 months while backpacking.
The really obvious convenience of the gravity system is the size and weight. $90 is a small price to pay if you`re a frequent backpacker looking for a system that will save you both of those.
I used hand pumps most of my young and adult life and they`re great `cos they clip right on but if you`re planning any sort of a serious excursion every ounce counts. Using a bladder bag and these would be ideal for a longer hike providing they`re durable. I would seriously hate to pop one.
Must’ve been a scary spigot…
Filters are just expensive, so $90.00 isn’t that pricey given the market. Perhaps it is expensive when you consider that it is just two plastic bags, some tubing, and a filter… I don’t consider the ability to filter water in the wilderness a “luxury”, however. It’s essential.
Which brings me to the point that if you’re car camping, you should probably just throw a few reused milk jugs of tap water from home in your trunk. No filtering necessary.
Also, one thing that is nice about other hand-pump style filters (like the MSR MiniWorks EX) is that you can screw them directly onto your Nalgene bottle, or numerous other hydration bladders that have the same threads. This means you don’t have to transfer water from container to container, which often wastes water (spilling) and time. But you could also get creative and rig a gravity system up to do the same.
Anonymous: The point about using a Sharpie is to differentiate the bags more clearly to be extra sure. i.e. I screwed up and put dirty water in the clean bag without thinking. Shhhhhhhh, don’t tell Lisa.
Late to the thread, but I’ve been looking into any commercialised virus filtration methods and Sartorius are the only ones with a product.
But intended for lab work, where people are producing DNA, RNA or in vivo treatments. Actually crazy stuff – 20 nm.
PDF warning!
Sartorius product sheet for ViroSart CPV Microcaps
Sartorius manufacture 0.2micron filters and larger for hospital scenarios, which are also used for IV drug users.
I hope the day that viral filtration is mass marketed is the day I read about it here!
FYI – 0.2 micron won’t filter out virii, but should handle bacteria and amoebas, so be wary. Most notable: the hepatitis virii will happily go through 0.2micron.
Virus filters are available, but they aren’t cheap, and rarely seen outside of research labs.
Here ya go. 20nm filtration in a bottle.
Mike