Backcountry Water Treatment, Part 6: Ultraviolet Disinfection 

Oddly enough I emailed Steripen's customer service last week after noticing that I can't find any in stock. Here was the reply, "Thank you for your email. The supply chain issues that are effecting a lot of industries are also effecting the Steripens. We are hoping we will have more Steripens in stock to get to our outdoor retailers, but I don't know exactly when. Late August at the earliest most likely. It is the computer chips and some other components that are the problem. Depending on the model you are looking for, some of them are more readily available than others. Steripen is not being discontinued."

Your series is a college-level yet very accessible and understandable course on water-borne pathogens and how backpackers can best protect against them. I’m not aware of any other resource like yours in any medium: lecture or writing. THANK YOU for doing this.

You Sir have earned your Engineering Doctorate in Skepticism. So glad to have found your channel. At first, I thought I would skip through the long vids, but it's impossible not to appreciate every detail you have uncovered that takes the “marketing” terms we are fed from manufacturers and agencies to see the truth. Thank you for your “rabbit hole” dedication to bringing real information to light.

This is the most relaxing and palatable way of getting this information while also diving into the science behind it. 10/10 love it and hope to see more

Awesome video, you laid everything out, no bs. When in the Backcountry I like the piece of mind of having fail-safes and backups. I could see it going in a kit with a saywer a charcoal filter, and chems as backup. Using a 3 stage setup with UV as the last stage, it could theoretically give you removal of bacteria, cysts, viruses, metals, plastics, and chemicals. This would give you flexibility as to what water you could drink. With a battery bank and a portable solar panel you can extend the life considerably or indefinitely until the unit goes bad. The biggest benefit for me, since I'm paranoid, is the piece of mind. With filters you wouldn't know if it was actually working in the field, it could freeze accidentally or it has a manufacturer defect. Chemicals take time and without a watch you might not wait enough, or waste time waiting. With UV you literally see it working, (with safety glasses of course). This is the biggest pro of one of these for me. Yeah it may be a pain, it may be dead, it may break, but I will know that it's not working. I can adjust accordingly without risking drinking contaminated water without knowing. This is more of a survivalist take on it rather than ultralight.

Your info is unparalleled. Thank you for putting this out there and doing the extensive research you do. I work in water treatment and I have been able to learn from your content. Also, I’d say that this is a series that all backpackers and even overseas travelers should watch. Being skeptical about your gear is smart. Gaining knowledge on “why” one product works or not is indispensable.

I found this channel when Mark Young gave you a "shout out" on his RU-vid outdoor channel. He rightly stated, "you can go as deep as you want into the subject of water treatment, probably more than most of us will ever need to know." After watching the series, I am happy to say that this is true and that I appreciate your effort in gathering, compiling, and presenting so much information in one place. For us, there is enormous value in what you have created. I relocated to the Republic of the Philippine Islands eleven years ago. Water, water everywhere; however you dare not drink a drop unless you test first or treat. Water issues are exacerbated by flood emergencies during and after typhoons. I can go on and on, but I am sure any reader with knowledge of SE Asia has some idea about the challenges of contaminated water and insect-borne disease in this region. Next step, whack the subscribe button and let my friends and acquaintances know about this excellent information source.

Yours is one of the few channels that I am willing to sit through an hour "lecture". I always learn something new. Thank you.

As someone who is trying to get into back country back packing, I find these very informative videos to be of the most valuable sources!

As someone planning a hike across all of Japan, I greatly appreciate your videos, the amount of work you've put into them, and your attention to detail. I'll give you a shout out when I'm on the trail! 👣

Your video on caloric density and what actually is ultralight food was amazing! This one on UV treatments is well researched and eye opening. I’ve never used a UV treatment system. Not sure if I would. Thanks for another thorough video to help us sift through the mine field of gear out there!

Comment for the Algo. This channel is awesome, there is nothing like it, you should watch it.

It cracks me up that the series on water treatment was so often encroached upon by the sound of water from the outside. Wonderful series. I've been (nervous about) but in love with my Steripen + chemical backup until now. I may need to revisit that as a system...I think.

Thank you for all your hard work in assembling this information and presenting it to the community. Cheers!

I’ve used a SteriPen Ultra on several kayak camping trips, filtering clear lake water in the Adirondacks. Even when used by itself my partner and I stayed free of whatever pathogens may have affected us otherwise. However, on the last couple of trips I have started to prefilter with a Sawyer mini just to be safe. I’d like to note that the SteriPen has never failed to operate properly, but understanding it’s limitations is a must. I keep it in my emergency “go bag” at home, along with the Sawyer. Thank you, Gear Skeptic, for your outstanding contribution to wilderness safety and nutrition! 🪶

You are one of the best youtube channels I know. Amazing series. Watched some of your videos twice because it’s so detailed and I don’t want to miss any writing notes along the way. I was wondering if you’re going to make another video comparing different products and combinations of methods. A spreadsheet with a couple of leading products and there log redactions for each pathogen would be absolutely amazing. Love your content please keep up with the great work!!

It’s entirely criminal you ‘only’ have 16k followers. I’ve watched every minute of your videos and they utterly fantastic. So useful! Well done and keep it up! Just about to see if you have a patreon page for some more support.

Just wanted to say I've been through most of your videos now and they are excellent, as someone with a chemistry background it can be so frustrating being presented with all the uncited pseudoscience out there and I appreciate all the time you put into doing proper research.

Quality over quantity. I can't wait to see where this channel will be a year from now! One of the very few times I've rung the bell to make sure I don't miss anything.

This channel is like no other in quality and the information it offers thank you, and keep up the good work!

It seemed wen people did reviews in the past they gave it steller reviews. This sounds more practical. NICE JOG.

Great to see a new video! Will dedicate some time to this tonight, looking forward to it :)) thanks again for producing some great content mate

Dude please keep putting out the videos I live for this knowledge

Thank you for another wonderful episode in the series!

Been looking forward to this vid! Some of our high country in Australia has wild brumbies and always hesitant with water source.

Great work! Thank you for putting in the hard work and making this topic accessible for everyone. This series taught me a ton about water quality.

How do you only have 7656 views as of this date? Wow. You hooked me to all your videos. Fascinating and I’m learning something at the same time. Since I have a UV pen, Sawyer, Quckdraw and a Grayl as well as Aqua tabs before watching any of these I guess I am covered. Each has its own best use.

Thank you for another great informative video. I did miss your opening montage though!

As ever, a brilliant piece of investigation into the efficacy of various water treatments - thanks 😃

Great timing. I've watched all of your vids in the last fortnight! 🏞🇦🇺

Wow. Comprehensive as usual.

I absolutely love your work - Thank You! It is very much appreciated.

Another great vid here. Been working on some UVC ideas. Maybe even commercially viable. But one thing i always bring if I'm in canyon country is a flocculant. I have used Alum to great effect but recently switched to “Water Wizard for River Runners”. Its Polyaluminum Chloride (PACL) or “PAC” for short. I always carry a collapsible bucket, small squirt from the syringe, stir and wait about 20 minutes and it will turn the Dirty Devil clear!

I really don't know of another source that brings such debated topics in the digestible way it is presented. I salute you for taking away urban legends and sometimes plain stupidity. I thoroughly enjoyed the series and the info they provide. Keep up the good work :)

This was an exceptional series! Very thorough and comprehensive. I only wish I had seen it prior to making a recent filter purchase.

it's a start to a great day when gear skeptic posts!

OUTSTANDING! THANKS.

thanks for your curiosity, your effort, and sharing your findings.

your videos are on another level of quality, they are amazing! thank you so much for all this information! I would love to see a video about the P&G Puri Bag, and their performance in the infamous cow puddle.

7:13 As an Army vet this is so true 🤣 At the TOC's SCIF ECP they'd check your CAC, and if the SM didn't have it they'd be SOL, unless your PL was there to vouch for you. Glad I have my DD-214 now

Good video, well done. Bit of critical feedback and some information missing though. The guidelines used to establish the performance of the steripen only (or used to) refers to NTU. The drinking water guideline, US EPA UV DGM, clearly refers to UVT as the superior parameter, and that statstical and comprehensive testing must be performed to use NTU as a surragate for UVT. NTU on its own is meanginless. In Australia, we have lots of trees and plants that readily release tannins ( dissolved organics) into the water, which makes the UVT abysmally low. As a practical example of how significant UVT affected by dissolved organics, i like to campare a glass of tap water with a glass of sprite (or clear sugered soft drink). Both will have low colour and low NTU. However, One will have an acceptable UVT, the other will be so low, it makes UV treatment very difficult.

WooHoo New Video 😍👏🏼👏🏼👏🏼😁

Typo in "expsoure" at 47:55 in FYI. Good video. Thank you.

Brilliant. Thanks so much for taking the time and effort to do the thinking and research the rest of us should do but don’t have the time. 🤓👍🇦🇺

Sweet!

Lots of good info in this series. Does anyone have a table that would summarize the individual products or classes of products? The first take away is there isn't a silver bullet for a single lightweight product that handles viruses, bacteria, and parasites. Not a fan of gravity systems. Leaning toward combining chlorine dioxide & microfilter. Cheers!

Poor Wyatt. Very much liked the presentation and depth of information. OK, what is Part 7 going to be about. Thanks!

As with the previous 5 videos in the series, an excellent presentation. I've superficialy encountered all of these methods in the course of my career without ever considering their suitability at the time for backpacking use. I very much appreciate the systematic analysis and comparative evaluation which gives me the basis to make rational choices according to the attitude to risk. Many thanks for all your hard work.

I really appreciate your thorough videos. I'm curious of the make/model of your small virus filter. I don't recognize it.

I purchased a steripen for "winter use". For me, that means trips where daytime temperatures may be below freezing. I'm OK with the idea of sleeping with my Befree/squeeze during the shoulder season, but once it gets to freezing all day long, I don't want to have to keep up with keeping it warm. I don't get enough snow to melt for water and from your other videos, all the chemicals take substantially longer to work at near freezing temperatures which concerns me. I've played around with the steripen accessories including a green funnel and prefilter that sites on top of the nalgene, but I found these awfully heavy for what little they do. One option I've considered is using something like a millbank bag to pre-filter the water. It wasn't hard to find a food grade 5 micron filter that I might be able to turn into something like that. If I were on the CDT full of nasty cow ponds, I might consider something like the Puribag and flocculant, but I just can't see myself taking the time to actually use it unless the source was really awful looking.

Thank you. Very interesting and some new information for me. E.g. I didn't know about the mercury. I've been using Steripen Ultralight for years. I've been very happy with it. It's practical and it really is light because my backup is water purification tablets (2 grams) and first of all: fire. I also carry a powerbank for my camera gear regardless. And the risk of getting sick here in Finland is quite low anyway. Some backpackers drink straight from the lakes and rivers although the health officials recommend against it. I stir the water in a metal pot or kettle. I'm assuming that the light bounces a bit from the reflective surfaces before escaping which should make it more effective. And the shapes of the containers are quite optimal for high intensity of the light. But in any case, I'm not too worried about the effectiveness.

Filters with activated carbon adsorb viruses as well. That's why a couple of backpacking filters on the market are claimed to be water *purifiers* and not just filters even though they do not filter smaller particles than the Sawyer Squeeze. And Sawyer does have a water purifier that I have not tried yet, it's the *S3 dual filter system* . The key feature is it's *adsorption* that removes particles that are smaller than the filter matrix via ion exchange. I'm not an expert, just putting this on the table for people to look into. I notice that norovirus is not on any of the list talked about and that is the virus of concern on the PCT in the state of Washington at the present time although no one has scientifically identified it on the PCT but there was an outbreak in Northern Washington that was identified as coming from eating raw clams just a couple of months ago and it might be the same source as it can survive on surfaces for 2-3 months depending on material and temperature. Norovirus is the #1 suspect considering the previous outbreak and the symptoms and length of infection and maybe historical outbreaks in the area(?) I would not worry to much about extra zapping if no one on a busy trail is getting sick . . . If there is only a 100 miles section of the trail that is suspect do not use it on non-suspect water in order to save the bulb and the battery. Pretty much everyone carries an extra 20,000mA battery. Aluminum bottles REFLECT UV light so it might be best to use aluminum bottles that are unpainted on the inside. Acrylic absorbs the most UV and plastic bottles might only absorb 50%. Get a UV camera to test. If so then wrapping the bottle in Aluminum foil would help. Check out this video by Veritasium where he uses a UV camera on plastic soda bottles and they do not absorb UV light unless something in the bottle is absorbing it. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-V9K6gjR07Po.html . . . Physics Girl has a similarly edutaining video as well.

This is a diligently researched and analyzed video series. However, it begs the question, what is your personal protocol for water treatment in various situations? Could you please share it with us?

Another great video. Throughout this whole series you have mentioned that you may want to use an additional method or use a method twice if the water source is of worse quality. I would be really interested in a video that breaks down how to judge the approximate contamination level of water while out in the back country. You have mentioned that having cows or beavers nearby the source can cause increased contamination. What other things can a backpacker lookout for when searching for quality water?

Every video I watch on this channel i think: what did this guy do before he ( one can only assume) retired,? Current best guess is mechanical engineer in some pharmaceutical or other clean process production context.

i hope some company can develop a submersible uv led that fits through traditional water bottles

Wow… I came across your channel yesterday and have been binging your channel… you are amazingly thorough… if you want another rabbit hole to go down you could look at pretreatment of questionable water with things like flocculation solutions.

Really fantastic video. Did your previous videos on chemical water treatment address the impact on ones gut biome?

Love the series, but when is part 7, the one with the summary and bundling options based on risk tolerance?

I always bring Aquatabs for backup

Not sure if this came up in the video, but my only reason for ever buying the steripen was to use it in freezing temperatures in place of a filter to avoid to risk of my filter freezing. Looks like the steripen is slightly less effective in colder temperatures, but should be fine as long as the water source isn't too turbid or terribly contaminated. I've only used it on one winter trip so far, but it worked fine. Other than the winter time, yeah, it's probably not preferable to a filter in most cases, due to all the cons you mentioned.

I'm disappointed someone else has watched this before me. Thanks, @gearskeptic

The video Personal Hygiene For Soldiers U.S. Army says boil water for 10 minutes. Why can't you just get on board. Thank you for all effort you put into this.

The use-case for me when it comes to UV systems is as a reliable solution for pretty short trips, places I can easily take water, but would like a solution that should I need to employ it, doesn't need maintenance when I get home. I have a couple trips I do every year where this is a possibility, there is tank water available should I need it, but I'd like to treat it. I can use one of my filters, but then I need back-flush/drying time. This is a concern when the relative humidity isn't going to drop below 80% for a few months. It's also an easy solution in the case of a boil-water advisory. In fact in Australia, UV-based home water treatment isn't rare. Not the most common, but I've seen a few around.

Regarding inverting the bottle with the Steripen, I did this and had my pen fail after about 100 days of use. When I returned it to Katadyn I got an email back saying the device was full of water and very corroded inside. It had never been submerged or rained on. Water could have only come from leaking past the rubber stopper.

If it sounds too cool to be true then it usually is. Only used mine once on a short trip.

Tell us more of what the Lord hath said from the top of the mountain ! .. Always impressive .. I am but your vassal hoping to gleam some knowledge from your cogent depths

Do you know if there's a way for the average person to test what pathogens are in a a container of water from a source in the back country before and after one filters/purifies it?

What about water distillation? Is it possible to remove all harmful materials(pesticide, heavy metals, chemicals, viruses...) from water on hiking that is also practical? There was an incident years ago in my country where vinyl chloride(number 1 cancer inducing chemical in eu) got into a deep water reservoir which was used by a local mineral water packaging plant. Which really questions my decision on what sources of body of water worth to use as a source and treatment that worth using on hiking.

OK. first, don't try to treat mud. 1 Filter the muddy water through your t shirt until clear / cloudy . 2 Then a micro fiber filter , 3a chemical treatment , 3b then carbon filter to remove the taste OR 4 heat treatment until pasteurized, . At the muddy dam, I would dig a small hole 3 ft or more from the water edge to below the waterline and remove all the water. When it refills I would empty it again, and again until the water is clear Then collect and filter and treat the water.

I watched this and had a moment of sadness when I realized that I have run through all of your content. Since you have sciencified everything, I wonder if you'd consider a series on the point of efficiency of other backpacking choices, like base weight's effect on speed and calorie burn. I'm sure you could apply some fuzzy math to arrive at a percentage of TBW before pack weight affects performance. Or, as your name indicates, a series of shorter videos looking at the claims of a broader category of backpacking equipment with a skeptical eye. Sleep pads and the R values that everyone relies on, for example.

48:30 Wait, what is that "71 gram filter"?! I watched/listened to all six hours of your discussion, but didn't catch which filter that is. Probably just me, but I lost your conclusion in all of the detail.

Sound issue?

4:20 Looks like it should be ribbed for the microbes' pleasure

I think you have one area still unexplored: oxygen water treatment. See you in 3 months.😉

Why not just put your bottle of water in the Sun? Natural UV, and you don't need gadgets that use batteries.