Backcountry Water Treatment, Part 4: Ultrafiltration 

Thanks! I appreciate that!

I second this :-)

I didn't even realize this was almost an hour long until I read your comment!

@@GearSkepticyour videos are awesome Thankyou. Best on RU-vid

Thank you so much! That is very generous of you, and I sincerely appreciate it.

You’re very welcome! I hope it helps!

Very kind of you! Thanks!

Egad! How would I handle that many comments? 😜

Good point! Part 7 is going on the planner…

Thank you! I appreciate you saying so 😁

You are most welcome, and thanks very much!

@@GearSkeptic I just finished a 5 day hike in the Gila National Forest. On day 4 I didn't encounter a stream with water for several hours and by then I needed to resupply my potable H2O. I came across a nasty, foul looking, shallow stream in an area where livestock fed and watered. So, I first "filtered" the water through my hankerchief. Then I filtered that through a Sawyer filter. I then treated that water with my Aquamira Chlorine Dioxide A/B system. Lastly, I filtered the water again as a drank it. Whew! If I'd had my steripen I would have used that as well. I thought of this video the entire time, too. Thanks again!

Yikes! Sounds challenging, but I’m glad you were okay. Type 2 fun!

Thanks very much! That is kind of you to say.

It only takes you a day to absorb a single GearSkeptic video? What is your trick, as I have to go over and over them time and time again

Most kind of you. Much appreciated!

Thank you! Very kind of you and I appreciate it.

As always, you are most welcome! 😉

Who said 1 in 50 was an overall rate for the whole trail? The tables of trail waters sampled show many locations tested negative for coliforms. You cannot extrapolate the odds from a worst-case location to the entire trail. Then, not everybody fills 4 liters at a time. For those that take only one liter from that particularly bad spot, their odds aren’t 1 in 50. Some others will skip over that bad spot entirely, happening to leap frog it because they’d gathered water previously from a place perhaps not so contaminated. Again, the presumption that 1 in 50 is some kind of base rate is unsubstantiated. It is expressly a worst case scenario. Not everyone stops at only the worst spots each time. Not everyone gathers 4 liters even if they do hit one of the bad spots. And, don’t forget the difference between infection rates and sickness. Some infected can be asymptomatic spreaders. And of those, many will go unreported as the illness is often known as what is “self-limiting”. Even amongst those who seek medical attention, there is rarely an actual genetic diagnosis of what caused the gastroenteritis. But, if the question is simply whether or not there is a common understanding that you have the possibility of getting sick on trail, just Google it. I found no shortage of first hand accounts, and the routine advice to always treat the water.

Thanks very much! I will try to keep my eye on the ball 🙂

Thanks! I appreciate that and am very glad if it can help!

Thanks!

Thanks! I appreciate that!

Much appreciated! Thank you!

Another rabbit hole! 🤓

You are most welcome!

Never had a day of training! 🥸

Don’t forget the wormholes!

Sometimes the website people are not the spec people 😉

Thanks very much! It is kind of you to say.

Within the Ultralight community he's already a legend. 63k views on his food video.

It relates to the logical problem that you can't prove a negative. In this case, the negative statement is: "There are no viruses 4nm in size." That can't be proven directly. The only thing you can do is try to look up every single virus known to science, in order to establish a list showing how everything is larger than that. There's no single-search I'm aware of that will do that for you. The problem is, you can never be sure there isn't a 4nm virus out there that you just didn't catch. There might be one documented in a source outside the NIH. There might be hits that didn't come up with your particular search terms, or via the engine you used to search with. Logically, it always remains a possibility. So, proof-wise, the better approach is to try and establish the truth of the positive version of the position: There is a 4nm virus. Not only can that be proven conclusively, it would have been the much faster way to go. One 5-second Google search that returns an electron microscope measurement of 4nm and you're done! The problem is, that quickie search returns no hits. This doesn't prove the negative, though. It just fails to prove the positive. So, you end up faced with two choices: 1) try to prove the positive by tracking down the source of the factoid in the book, or 2) go the much, much longer way of trying to play process-of-elimination with the sizes of every known, human waterborne pathogen ever identified. It might seem like simply Googling "world's smallest virus" would suffice. It doesn't. The distinction "world's smallest" changes over time. Any given article you might find claiming the record could have since been superseded. It could also just be wrong. I found articles claiming Tobacco virus was the smallest, but knowing better I kept searching. Sure enough, I found Porcine virus was smaller still. That was the smallest I could find, but there could always be some other virus out there that was recorded as one nanometer smaller. And, another one smaller than that. Basically, establishing the truth of the positive statement would have been both more conclusive and faster...if it had panned out. Unfortunately, it didn't. So, I ended up having to do it the hard way after all.

Thanks! You know, I’ve tried to contact authors at least a few times. So far, haven’t had a single response. I won’t give up, though.

Thank you very much for the thought, but it is sort of a passion project for me, so no other reward than your kind comments is necessary!

😉

The First Need is an adsorption filter, not an ultra filter. It gets mentioned in Part 5.

Ooo…protein water 🤢

Thank you! That means a lot to me.

Good tip! I do have have some research for an eventual edition on solar disinfection. So easy to get sidetracked!

Thanks very much!

They put them in a Petri dish and let colonies grow until you can see them well enough to count.

Thank you very much! Those are kind words, and I do appreciate them!

Good to know! Thanks much.

@@GearSkeptic Also, This was a very informative video and topic. Thank you.

My pleasure! I only hope it helps.

You are most welcome! I figured, after doing it for myself, I should share in case anyone else was interested..

They can grow mold. Sawyer recommends giving them a diluted bleach backflush and then letting them dry out on their own (don’t seal it in a ziplock bag).

That's usually because most filters with an adsorption element are also using a traditional filter for the bigger stuff. So, that filter will tend to clog like any other and reduce flow. You sort of have to trust them that the filter will clog and slow at a rate matching the saturation of the adsorption media, however.

I guess it may be time to turn in the old filter and use a frontier max- thanks

You are one video away! Part 5 deals with just that.

You are most welcome!

You are most welcome and thank you, too!

You’re welcome! 🤓

I break it down by considering which threats to worry about given the environment you’ll be passing through. If you will only be drawing water from wilderness sources largely unaffected by humans, a bacterial filter like a Sawyer seems like an efficient choice. If crowds of people use the waters, they can introduce viruses as a threat (like recreational areas with lots of swimmers). If there is risk of contamination from industrial or agricultural activity, then chemicals might be an issue. I usually bring a Sawyer for general use, and some chemical tabs for backup should I encounter bad water and have no choice. I’ve also always got the means to boil. Since it’s light and small, I started carrying the Platypus carbon element in case the filtered water still smells or tastes bad, though I haven’t actually bothered to use it yet. I did buy one of the Hydroblu elements to try out, though. If you’ll need to source water from farm or urban runoff, or from water where motor boats can leave chemicals, I’d stick with your Grayl. Hope that helps!

@@GearSkeptic It certainly does, thank you once again, even your comments are comprehensive! Cheers

Yes, that is next!

Thanks!

Thanks much! Very kind of you. I’m not actually signed up for the affiliate program, so YT gets whatever the ads make. I had originally intended to stay ad-free, but they changed the user agreement a year or so ago, and now they can put ads in for their own sake. I suppose that’s fair. They do provide this service for free!

@@GearSkeptic Your donation to the community is what all good creators aspire to do. If you ever decide you want to be compensated for your efforts, a 3x5 pocket sized notebook field guide would be a great way to publish this info and sales would help cover costs to invest back into the channel. Even if its a print on demand file that people buy for a few bucks, it would cut down on your costs. I think it would leave a lasting impression on the community of backpacking and hiking as your methodical approach is sorely missed in many hobbies. I personally have used your info to overhaul my emergency gear and look forward to a possible guide on carrying water and maybe footwear, the largest items people usually have to contend with. My goal to hike the Appalachian trail is a slow burn and your channel has made it seem possible.

Fortunately, I have a ton of ideas in the queue. Unfortunately, I’m super slow, so it’s gonna take a while!

Thank you very much!

You’re most welcome! I hope it helps.

Thank you! Much appreciated.

🥸

Thanks! I agree, and sometimes “public knowledge” can be wrong.

Thanks! I will check out that study. I’m knee-deep in adsorption and ion exchange stuff right now, for Part 5.

Cause and effect can be tricky. Lots of things could be happening. Those two filters are pretty good, unless you’re facing viruses. Many seem to assume viruses aren’t a threat in the States, but they are out there in some places. It could explain why some still get sick despite filtering (with devices only good down to bacteria). As you say, hiker hygiene is also a culprit. Many of the researchers from the studies I’ve found agree. And, how you use the filter (and handle dirty water) could be an issue. Some folks don’t use good “lab practices” with handling contaminated equipment.

Thanks!

Thanks much! That’s basically what prompted me to dig into it. Reviews would just talk about price, usability, and things like flow rate…but never even touch on efficacy.

Thanks! I appreciate that.

Hmm. That’s a bit concerning. Something to keep in mind.

Thanks much!

Thank you! Very generous to say 😀

Thanks very much! I really appreciate it.

Thanks! I did not know about their travel sizes. I will check them out!

Thank you! That’s very kind of you to say, and I take it to heart!

You are most welcome, and thank you! I appreciate the kind words.

😊