Ep 74: Backcountry Drinking Water, with Dr. Vince Hill
Dr. Vince Hill is the Chief of the Waterborne Disease Prevention Branch of the CDC. In this episode, I got to pick his brain about backcountry drinking water. If you’ve ever spent a night in the backcountry, you’ve probably had to deal with water filtration or purification. We covered three main topics in this episode: the basics of contaminated water, what causes the contamination, and how we can fix it to make water drinkable.
CDC Guide to Backcountry Water: link
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Katie
You're listening to the Fish Untamed podcast, your home for fly fish in the backcountry. This is episode 74 with Dr. Vince Hill on backcountry drinking water. Okay, I think we should be good to go now.
Vince
Okay.
Katie
So yeah, we'll redo this intro a little bit. I had mentioned to you that because this is a fishing podcast, normally I get people's background on fishing, but because that doesn't really apply here, if you could just go over again what brought you to the CDC and you were also telling me about how you got interested in water specifically with the CDC. So go ahead and run me through that again.
Vince
Sure, sure, sure. So yeah, so I, since high school, have always been interested in environmental science, engineering, and kind of those topics. And so I just, in college, was in an environmental engineering program and had some projects that were around water treatment and, you know, wastewater microbiology and things like that. So I've always been kind of interested in water and wastewater treatment and then practiced as an engineer for a few years, but then went actually to and got training as my PhD in environmental sciences and engineering at the School of Public Health at University of North Carolina, Chapel Hill. And that really got me really interested in the public health aspects of water and wastewater treatment and focusing on water quality, safe water practices and things like that. So fortunately for me, there was a position here at CDC and I just really just enjoy, you know, talking to people about safe water practices, how to make water safe, water treatment and related practices around safe water and hygiene.
Katie
Now I heard you originally on the Hunt Backcountry podcast, which is how I got ended up getting in touch with you. And it's, it's interesting because a lot of times when I'm hearing about safe drinking water in the backcountry, it's in the context of somebody who is doing that, not from kind of the actual CDC wastewater that side. So do you have a specific experience with backcountry drinking water, or is this just something that's applicable across disciplines? And so it doesn't really pertain to one area versus another, more so just what's in the water and how it's treated. Is that kind of universal? And is that why you were able to speak to that?
Vince
Yeah. I mean, so there are certainly general principles about what can be in water, filtration, disinfection, how to make water safe. So whether it's a drinking water system or you're out in a back country, those kind of general principles about the microbiology of water and treatment, et cetera, are all there. And so we can talk about those in more detail. You know, I would say, you know, we -- and CDC, we do have -- because it's such a common practice. I mean, we want to make sure we have guidance that people can use to kind of fit the application or questions they have when they're going about their lives, daily lives, or when they're out recreating. And so we know that hiking, fishing, backcountry, you know, recreation are really popular. And really healthy and just wonderful things to do. And so when people are out doing those things, they may have questions, and they do, about, you know, it could be hygiene practices, could be food safety, but for us right now, talking about water safety, and so we do have specific, if anybody's interested, they can go to our search, whatever your search engine is. I think if you do CBC, backcountry, water, you can probably find our web page that has a lot of the, you know, filtration, disinfection guidance and some other kinds of, you know, hygiene and safe water practices for this kind of general area.
Katie
Do you folks receive a lot of questions from people who are like, "Hey, I want to go backpacking and I want to know how to drink water safely." Does that make up a large proportion of what you receive?
Vince
Maybe not direct questions, certainly maybe a little bit broader when people are traveling. So if you think about being outside of your normal area, I'm outside my home, you know, whatever, I'm traveling internationally often comes up, or if you're traveling recreationally within the United States. So basically being outside of where you're used to, and what do you do, how do you... Can you trust the water? If not, how do you make it safe, et cetera? So we get that more broad set of questions, but we certainly get outbreaks of disease, waterborne disease, related to back country settings, park settings, et cetera.
Katie
Interesting. And you mentioned, like, how do you know if water is safe? And I sent you kind of three general categories I think I want to talk about today. And that is water quality and location. Like, you know, I think people maybe have a misconception that, oh, this water looks really clean, so therefore it's clean. And obviously that's not the case. But, you know, how does that compare to water that looks very obviously dirty? So that's kind of one topic. The next one I wanted to cover is what is in the water that's causing the problems. And then third is, you know, how do you fix it? filtration versus purification and things like that. So maybe a good place to start would be just where water is and how it looks and how that affects how safe it is to drink. Like if someone's going out in the woods and they they come across some water, what considerations would you give that person as to deciding what to do and what might be in that water?
Vince
Yeah so I mean I think you know what's important to remember first you know is that there are many sources of water contamination. So including some things are naturally occurring. Naturally occurring toxins that can be from microbes that occur in the environment. There can be chemicals that are naturally occurring based on the geology of wherever you are, so arsenic, fluoride, these kinds of things can just be naturally present. And of course, local land use practices, so fertilizers, pesticides. If you're in a farming area, all those things can be in water. But also, of course, thinking about fecal contamination, feces from wildlife, birds, deer, other kinds of animals. Of course, if there are farms with cattle and other things as well, those can get in there. Frankly, people and their septic systems can get into natural water bodies. So there's all sorts of sources of these kinds of contaminants that are out there. And you can't necessarily rely on just your visual observation to really say whether the water is safer or more risky.
Katie
When, I know you mentioned like lots of different things there and I think what comes to mind for a lot of people who are recreating outside is The I don't know if it's viruses bacteria what what category each of these falls into but you know I'm going to eat some sort of microbe and it's going to make me sick But you also mentioned things like heavy metals Which is not something that I think a lot of people think of Is that a big concern when someone's you know walking through the mountains and comes across a mountain stream? Or is it more are we talking more about the eating some little bug that's gonna make you sick?
Vince
Yeah, no, that's a great question. And I think it's a matter of what you can do also to decrease your risks of getting sick from drinking natural water. So a lot of the filters or water treatment methods, products that are available to, you know, hikers, you know, backcountry recreation, it are really kind of geared towards removing microbes. So, you know, they'll have a certain filter size, pore size, etc. Or they'll have, you know, there's a disinfectant there. So they're really kind of geared towards the microbes. So chemicals, that's a little bit challenging to, you know, to deal with. Now, if you have a household water filter, you know, there's, you know, reverse osmosis, there's ion exchanges, all these kinds of things, but those tend to be bigger systems. And I don't think there are many, if any, water, you know, common water purification products that are available to backcountry recreation, you know, people who are going backcountry that that really kind of work on those. So it's really, yeah, so I think you can do what you can do to make water safe. And usually that's around filtration and disinfection to kind of make it safe from the germs that might be there.
Katie
In the case of something like a chemical or heavy metal, if they are present in the water, is that something that you could detect? Is it worth avoiding water that you know could be contaminated with these things? I assume if you see a mine draining out into the creek, you don't want to drink from that creek. But is there any other sort of visual clue that you could say, "Hey, not related to microbes, but related to actual chemicals or metals, Is there anything visually you can see in water that would make you say, "I'm not going to drink from this source. I'm going to go pick something else"?
Vince
Yeah, that's a great question. So clearly there are some visual signs of water contamination, including water that's colored or cloudy, water that may have a sheen on its surface, and water containing sediment or floating particles. So that type of lower water quality that you can visually see like that may actually make it more difficult to effectively treat the water, you know, if it's particularly, you know, cloudy and got a lot of particles in, et cetera. But I would say, you know, certainly those are visual signs. Another area that we work with here at, you know, at CDC and my group around algal blooms. And so I know a lot of settings, especially, you know, if there's a color to the water, it could be because there are algae or cyanobacteria that are present, and some of those may be harmful. And so it's the toxins that they emit that are actually what cause harm. So I would say, you know, clearly if you're seeing green water or cloudy or whatever, that's the kind of water you say, "Hmm, this is probably not the best water to use." So hopefully folks have prepared for those kinds of situations. So I think situational awareness is important. If you're going into a really pristine area, probably not going to run into a lot of those issues with really cloudy water, colored water, et cetera. Further downstream where rivers and streams are draining a larger landscape, you've got more sources of potential contamination, situational awareness would say, "This is probably a little bit risky. Even if I can remove some of these microbes that are there, there might be some other things in there that my filter's not rated to remove that I should be worried about."
Katie
Right. And I think luckily most of the places that at least people listening to this show are probably getting their drinking water in the backcountry. Those aren't as big of a concern. Like I think the only off color water that I've had and filtered is just like regular old this water looks a little muddy. You know maybe it rained recently and there's some water washing in and it's just clouding up. But that's different than if I came across like green water you know that would that would definitely put something off in my brain saying maybe I should think twice about this so we don't have to spend too much time on that I just wanted to cover it since it's something that I think people aren't thinking about as much as they are on the microbes but I do think the microbes are where we can move next because that's probably the vast majority of what people are concerned about so what kinds of microbes are in the water that people should be concerned about?
Vince
Yeah, so there are a huge range of microbes that can be in water, bacteria, parasites, viruses. And it's good to have some sense of the differences between them that can impact the kind of water treatment that you choose, a product that you choose, a filtration system, et cetera. So we could go into some detail on kind of differences between some of those microbes. And I, you know, so for the parasites, there are, you know, some pretty well-known diseases or pathogens that are parasites that we'd be worried about. Cryptosporidium, Giardia, a lot of people, you know, know those microbes and those diseases. Bacteria, it could be pathogenic E. coli, it could be, you know, other microbes like that, Campylobacter, et cetera. viruses, you know, there are enteric viruses, norovirus is a common one in water, et cetera. So those are kind of some of the names that people might come across when they're reading about or concerned about water contamination from microbes. But first off, the kind of first bigger class, and I mean bigger by size, are the parasites. And so they're larger than bacteria and viruses, not to get too technical at the size range, but four to like 14 microns or micrometers. And I think that's actually important to know because I think a lot of filters that are commercially available might have like a one micron pore size. That's pretty commonly that you come across that. And so those one micron filters are rated to remove these parasites. So they should be highly effective at removing these parasites. And I think that's really important because some of these parasites, like Cryptosporidium, are tolerant to common disinfectants, like chlorine or iodine. So if you were just dropping in a chlorine tablet or drops or whatever that is, we can talk about bacteria and viruses. Those are generally effective against bacteria and viruses, but wouldn't be effective against crypto. And even Giardia, you would need really long exposure times or you know, times to hold you know, the the water before you drink it. And so the filtration part is really useful for removing those parasites. Now filters can also be effective depending on their their pore size, their rated pore size for removing bacteria. So bacteria now are a class that are smaller than you know, 10 to 100 times smaller than than the And but generally speaking, the disinfectant, so even if the filter doesn't remove the bacteria quite as well, or you don't have a filter, chlorine tablets, iodine, these kinds of chemical disinfectant products can be highly effective against bacteria. If you follow, again, always follow the manufacturer's guidance and really, really take that to heart. You know, go, "Oh, I don't feel like waiting a half an hour," or whatever it is. You know, really take it to heart. science behind it and just you know hopefully you can and people can be patient and give it the full exposure time for the product to really work effectively. And then viruses are really the hardest to remove. So one thing to note for filtration because we might talk wonder about kind of filter products. So filters that call themselves ultra filters and are rated as ultra filters, that's a technical definition, those should be effective in removing bacteria and parasites. Some of those ultra filters, it depends on really how they're rated, could be effective against viruses, but I think a lot of the common water treatment filters that are available out on the market aren't necessarily rated to remove viruses because the pore sizes have to be so small that it takes a lot of force and pressure to push water through those tiny, tiny, tiny holes in the filters. And so that means either... Usually it means is that you can't produce as much water in a certain amount of time because it just takes so long and you get a relatively small amount of water that you can filter in a certain amount of time. So often the viruses might still be present. So I think we often look for, I think the best approach, if you can, if people can afford it and it's available, is to do filtration followed by disinfection. You can use both of those procedures. You'll filter out the big things and the things that might be resistant to a disinfectant. And then if you can disinfect the water, then it leaves a residual and it makes it safer in case any other contaminants gets introduced, you have a disinfectant that's still there present.
Katie
Yeah that's really good to know and I think we'll get into the actual you know cleaning the water side at the end but I think there may be a misconception that when you're filtering it that everything's just gone like the water is just you know crystal clear and remembering that the filter has a size and there's things that might not get trapped by that is that that's a good thing to keep in mind. In terms of these three main categories the parasites bacteria and viruses you know I think the one people hear about the most is Giardia. Is there one category that kind of is the the heavy hitter? The one that you're really focused on? Because you said that Giardia is a parasite. So are parasites kind of the big ones that really cause the most problems? Or do they all kind of hit equally? And what happens when you get something like this? Do you need to fear for your life? Do you get sick for a couple days? Do you really need to get medical attention? Just what's kind of severity of what happens if you don't properly clean your water?
Vince
Right, right. So, you know, the most, focusing on sort of the symptoms of waterborne disease, I'd say, you know, the most commonly reported symptoms are, you know, diarrhea, vomiting, stomach cramps, and fever, these kinds of sort of, usually self-limiting. So you've got it for a while, very uncomfortable, et cetera, and most of those being relatively self-limiting. Sometimes you can get other things, depending on the water you're in, but I think for people who are fish, well, if you are actually in the water, fishing, and so your skin's exposed, sometimes you can have either skin infections or reactions to things that are in the water. So sometimes you can get rashes and those kinds of things as well. So it's not always about the gastrointestinal symptoms, but sometimes other parts of the body, if they're exposed, can be impacted. Even eye problems and things like that, if people are dunking their heads in, we get reports of disease related to microbes that I'd say though, you know, so for most of those microbes, you know, most of the viral and bacterial infections, you know within say 12 to 14 hours you might start, you know Experiencing symptoms and usually it's those that you know, I mentioned that are self-limiting But some of the parasites one thing it might take a little bit longer to see symptoms. So maybe a week to two weeks So the parasympathetic that's kind of a hallmark of parasitic infections. Most of those also are self-limiting However, you mentioned jar D. One of the things with jar DIA is that it actually can last longer Giardiasis can last for two to six weeks But actually for some people can result in long-term complications including arthritis irritable bowel syndrome.
Katie
Yeah, I feel like that's not something that comes to mind like years later. Even with Giardia, when I've heard people have cases, it's like, I felt really, really terrible for a couple of weeks. And then they get over it. And I think the thought of being stuck in that for a year just sounds terrible. Are there any that would be considered life threatening? And obviously something like diarrhea could be if you're stuck out there for a long time and didn't make it back for whatever reason. I'm sure that that could cause dehydration or something like that. But is anything going to just acutely affect you to a point that you don't survive? Or most of these just really, really, you just don't want them?
Vince
It's more that you just don't want them. And they're really, you know, yeah, I mean, you're out there, you know, enjoying yourself and potentially, you know, you could be getting sick while you're out, right? You know, trying to have, you know, a good time with your family or friends or whatever. So you've got that, or you're bringing it back to your family and friends, and you don't want that either. And so I think, you know, that's, for most of these, like I said, they're self-limiting. Again, you can have longer, prolonged infections with some of these microbes. But there are some pathogens that, you know, and I think it depends, right? It depends on the pathogen. Some of these can cause bloody diarrhea. Some of the E. coli infections can get very significant in what they can cause. And so you can have complications, especially for, you know, the very young, elderly, or people with weakened immune systems. So again, and even if, you know, even if you, who are recreating, aren't in those categories, but then you're sick and you bring that back home, but you've got somebody in your family who falls into one of those more kind of at-risk categories, you know, you can get transmission to others and cause pretty serious illness in others as well. So just in general, I think it's, assume the worst, not like, "Oh, it's not a big deal. I can just get over this." Because you just never know what might be out there that you get exposed to that maybe you bring home to somebody who might have a bad reaction to it.
Katie
Right. And is there any sort of different guidelines around something like a spring, where you're seeing the water coming straight out of the ground? Because I know people talk about drinking straight from springs. Tend to have a different view of those than I do of you know You just come across a stream in the woods and who knows how long it's been flowing and what's been walking in it upstream Are there different guidelines for something that's coming straight out of the ground?
Vince
So not not really. I mean, yeah Clearly there there is that tendency to look at water like that and go. I know it's source It's coming out of the ground that cetera and looks clean But looks can be deceiving especially when we're talking about water quality and germs because you just you know, you can't see them So, you know, untreated spring water, mountain stream or lake water, you know, may look pure, but it may be contaminated with bacteria, parasites, viruses, or, you know, some of the other contaminants that we've gone over. So really there's no natural water source that you can say is 100% safe to drink without water treatment.
Katie
Right. Okay.
Vince
There's always a risk from drinking untreated natural water. Yeah. As we mentioned we already talked about you know higher elevations versus lower elevations and there might be some relative risk between those two But even if you're at the higher elevations, you're like, oh, this is mountain pure water, you know Really? There's no hundred percent safe water that unless you make it safe.
Katie
Sure. I'm sure, you know, in your position at the CDC. There's no way that you could just say yeah that's fine to drink because that wouldn't be a good look. So it sounds like you know, maybe one is relatively better than the other but at the end of the day if you've got the if you got the means to clean it then just clean it.
Vince
Right and have A plan hopefully, you know, you've you've made a plan ahead of time and you've you know You you can take action to protect yourself just in case.
Katie
Yeah So this might be a good time to transition then over to the actual cleaning of the water There's a couple different Methods that I wanted to discuss. I know we've already talked about filtering versus purifying I think those are kind of the two big ones that people do but I know the the UV filters are also a big or not UV filters, the UV lights are also a really common thing that people use these days and also boiling which has you know been around probably longer than any of these. So those are the main four. If there's any others that I have forgotten I'd love to hear about those as well but I just want to hear about your opinions on those four and when they're best used.
Vince
Great well maybe starting with the kind of tried-and-true old style water treatment method boiling, as you mentioned it, right? So, you know, I mean, boiling has, you know, very high effectiveness in killing really all those microbe classes, parasites, viruses, bacteria. You get the water up to boiling, you're gonna kill them all. And so, you know, and there's guidance on this. People can look at our website, etc. In general, we recommend a rolling boil, so you can see the bubbles and the surface is rolling for about one minute. And that really should do the trick for really anything. And I think if you're at higher elevations, you know, and then you've got that kind of pressure differential, you know, versus sea level, then our guidance changes just the physics of it, and we recommend three minutes. So there's boiling. Boiling is the most complete and comprehensive way to make water safe from microbes. And so after that, we can focus on disinfection or, yeah, would you like to talk about disinfectants?
Katie
Yeah.
Vince
Yeah. So chemical disinfectants. So those are the, you know, either tablets or drops. They tend to be these halogens, so chlorine-based or iodine, although now I think there are some new products that are chlorine dioxide-based that people might run into. So I would say with with each of those the contact time is really important. So follow those manufacturers, you know guidance on those. And there are you know different aspects of it that are really important though. You know how warm, to some extent how warm the water temperature is, although that's not a major factor for people to kind of keep a thermometer with them. But if the water is turbid or cloudy, that actually can impact the effectiveness of those disinfectant chemicals.
Katie
Oh, really?
Vince
Because, yeah, the chemicals will, you know, it's a chemical reaction. So, you know, if you've got other, you know, organic matter or other things, particles in your water that aren't your germs, then those particles are going to contact the chemical and, you know, there's going to be those chemical reactions. So those chemicals, then less of it is available to kill the germs. So quite often, manufacturer's guidance may adjust for that. It may either say put twice the amount in as sort of a rule of thumb or maybe a longer contact time, et cetera. So there may be some guidance that even your products provide on that. Or they might just say, "Hey, we can't guarantee the effectiveness of this unless you've filtered the water or made it less cloudy or whatever."
Katie
So do those those products alter the palatability of the water at all like I I feel like I've heard people talk about iodine. I never actually used iodine I tend to filter and UV sometimes a combination sometimes just a filter but I Feel like I've heard that the iodine can Leave your water with a an undesirable taste. Is that is that the case a little bit?
Vince
I mean, you know and chlorine as well and you know and and so it can. To me, the sometimes that's the taste of safe water. So I taste a little bit I go, okay, maybe it's not the most pleasant thing in the world. But it doesn't taste like my water at home. But I know it's safe. Because I follow the guidance and everything. But yeah, it can. And I think iodine even changes gives you a little residual color, like a little yellowing of the water. And that could be a little off putting as well. But there are no health impacts for that. Although I think with iodine, there are some, there's some guidance on certain folks, I think like pregnant women and iodine, etc. So always read those, the directions in those kinds of chemical treatment products just to make sure that you don't fall into a category where maybe it's actually ingesting that chemical isn't good for your health.
Katie
That was going to be my next question is, you know, I'm sure a mouthful of chlorinated water in a pool before and it's not pleasant and I feel like sometimes if I've gotten enough of it I start to feel a little bit nauseated but is there any there's no real health impact that's just kind of a you know your body doesn't love drinking water full of something else.
Vince
Yeah I think I think that's just sort of a reaction that people might have you know mentally like you know treating water you're like oh I wasn't supposed to drink that so you know don't want to consistently drink pool water, but I think even the EPA guidance is up to maybe four milligrams per liter of chlorine, so that's a pretty fair amount of chlorine, and that's for consistent drinking. So the little bit that you get from these backcountry water treatment products, et cetera, are perfectly safe.
Katie
Okay, good to know. So then how about, I don't know if you want to do UV or filtration next?
Vince
Yeah, so for UV, so UV can be effective for, you know, inactivating microbes against some classes of microbes, especially. So the thing with UV, so it can be effective against many, frankly, a lot of the parasites. So we mentioned Cryptosporidium being tolerant of some of the disinfectant chemicals, the halogens, chlorine and iodine. Actually, crypto can be inactivated very easily and effectively with with UV light. So that's good. Again bacteria can be inactivated very readily with UV light. Some of the viruses may have a little bit of resistance to UV. So that's maybe one factor but really the biggest factor with UV is that you need the UV light to be able to contact the germ to inactivate it. Again, back to the kind of same sort of a similar issue with with the cloudiness of water that we talked about with disinfectants. Absolutely a factor with UV light. So if you if the water is colored, if there are other particles, then those particles can absorb and block you know the UV light from from impacting and you know damaging the germs. And if that happens then you're not getting effective kill of those germs. So without a doubt, if the water is at all cloudy or you've got particles, you really have to be a little bit concerned or you really should filter the water ahead of time and then UV it to kill microbes. So it's one of those that's a little bit iffy to use in the field that you really have to understand water quality a little bit better to effectively use it, but it can be effective.
Katie
Yeah, and that one's just convenient because it's pretty light and easy to carry. I've got, I forget what it's called, but the standard UV light that you use. And it's so, you know, throw a battery in that, throw it in your backpack, and it weighs a couple ounces compared to some of the filters that take up a little bit more space. But that's also because most of the mountain streams that we have out here are pretty crystal clear. And that's kind of how I've gauged that. I tend to go back and forth between the filter and the UV light based on is the water I'm going to be near going to be clear or not. And if I'm going to be in places that have like a lot of glacial melt that are going be kind of silty and darker then I'll take the filter because I don't really want to drink that water anyway when it's full of crap basically so I'm sure we'll get to that with the filtering as well like when that makes sense but I kind of view the filter plus a UV light is almost like bomb-proof you know you might get the full effect of both and have perfectly clean water at the end.
Vince
Right you know that makes that makes a lot of sense I know with UV light those tend to be for relatively smaller volumes of water that you're kind of personally consuming as opposed to a large volume that you want to have on hand at a campsite or whatever, gallons of water. You wouldn't use UV necessarily for that because in those situations when you do have a large volume of water that you might be worried, I don't know, hopefully people aren't you know dipping cups into their water like a bucket of water or whatever, but if you don't have a disinfectant residual like chlorine or whatever then you know the water can get recontaminated from the environment or your hands or whatever but you know that's usually not an issue with UV because you're not making large volumes that you're storing around your site.
Katie
Yeah I think my oh it's called the SteriPen that one I think you do like a liter at a time it's supposed to be stuck down in like a Nalgene bottle and that's I think maybe they have a recommendation if you do a larger one to do it twice as long but there there's definitely a maximum like you can't just stick it into a bucket of water and hope that it's gonna work.
Vince
Right.
Katie
So how about filtration because that that I think is probably the most commonly used one at for people I know is to carry a little filter around and maybe let's talk about when you would use a filter versus not and maybe the different types of filters and you know when they're good.
Vince
Yeah no that's great and so you're right they are so commonly used and there's so many different types that are available to consumers it can be a little daunting. I you know I a while back I was looking at different kinds of filters and even I was getting a little bit confused as to you know the guidance and the ratings and whatnot that there's there's just so many different types out there. So, you know, I think, so determining which type is most appropriate depends on, you know, kind of what you, what functions you want your filter to provide. So, because no filter, we talked about this, no filter is going to eliminate all contaminants, you know, microbes, chemicals, toxins, et cetera. So, so it's important to understand what they do and do not do. So, I think then focusing on the microbes again, definitely try to use a filter that has a pore size that's small enough to remove parasites. And so that's the most common ones will have a one micron pore size, rating, et cetera. So there are more kind of modern or not modern, but recent kind of developments in filtration that I've seen that where they seem like they're very, can be very effective for removing bacteria as well. And so I think those can be really great. Those might be referred to as ultra filters because they have a smaller pore size. The one micron filters might be called micro filters if they use those terms at all. But they can be highly effective against cryptosporidium. They might be rated, people can look for an NSF standard, 53 or 58. And so if it says it's rated to NSF 53 or 58, that means they're rated for the parasite removal or JARDI, a cyst or oocyst removal. But they're not gonna be effective for viruses, even if they have that rating because the viruses are so much smaller and they might be somewhat effective against bacteria if they have that kind of NSF 53 or 58 rating. But I think that's when the combination of filtration plus another disinfection method really is helpful. So one thing as well to note with the filters is there's probably guidance on kind of how to maintain them and a lot of folks might, you know, you know, you get back from a big trip and you don't necessarily want to put it through its paces to kind of, you know, put it back up on the shelf or whatever, but make sure, you know, to follow those because I think if water sits in those filters longer, or just focusing on that, you can get microbial growth. Bacteria and other things can grow in those filters, and they can, so potentially, I guess, can clog those filters, but it also can damage, depending on what the filter medium is, could actually damage the filter. So I think making sure that you're taking care of your filters as well will make sure that next time you go to use them, that you can depend on them and they work properly.
Katie
Yeah, that's another reason that I've kind of started to adopt the UV when it's appropriate. You know, when I've got clear water and I'm just filtering a bottle for myself, just because those filters, they get clogged really quickly and then you have to clean them in the field and they take a long time to use as well because they're starting to clog up. So you might be sitting there for 20 minutes really pumping with all your might to get the water through and then you get home and then you've got to clean it off again. It just seems like a lot more maintenance and a lot more hassle. But of course, there's times where it really makes sense, especially if you've got that cloudy water, partially for the ineffectiveness of some of these other techniques, but also because that will get all that stuff out. So then you can actually drink clear water, which I think is a lot of people's motivation for using the filter is to get nice, clean, tasty water at the end. So if you're done with filtration, one thing I wanted to bring up that you mentioned was the recontamination of water, because that's something that I occasionally hear happens to people and it's always like in the back of my mind of like, is that drop of water on the rim of my bottle? Was that filtered water or was that a drop that came from somewhere else? How big of a concern is this? Because obviously it can happen, but how much water does it take to make somebody sick or can make somebody sick? And how could that happen that you could get a little drop of water on the rim of your water bottle, let's say, And that little drop of water could contaminate the whole thing. What's the reality of that?
Vince
Yeah. You know, it's hard to kind of give real direct guidance on that. Because it really depends on the water that might be contaminating what you have, your water bottle or your water container. Where did that come from? And what the quality of it was, et cetera, et cetera. In general, if it's a little tiny drop of something, and it's rainwater or something like that, then that's not gonna be a risk. If your water bottle falls into the lake or river or whatever, then you might wanna wipe it off before you go then to uncap it or whatever. I think what we more often see with kind of recontamination of water is when the water is in kind of an open, a large open mouth container that you can actually dip into. That is classic, you know, chance for an igloo cooler or something like that that might be out, you know, like a picnic or whatever. Those are often kind of get recontaminated 'cause people are filling them from above and they're dipping into it, et cetera. That's not typical, I would imagine, for back country settings and fishing, et cetera. But clearly you wanna have storage containers that have a narrow mouth that can be sealed. And so the water you put in there, there really shouldn't be any real meaningful risk of contamination. The other thing to note though, is when you have a tap on a water jug, and so you've made your nice water nice and clean, but you've got a tap to get your water out. The taps, those taps can get contaminated. So you might touch it with your hand or maybe a rag touches it. Something that might be contaminated gets on the tip of the spout for these containers. So it's not the water inside that got recontaminated, but the water delivery kind of container did, or the valve. And so those have also been kind of causes for outbreaks and things like that that have occurred. So I think it's just being careful about your hygiene around the water. You've gone through all this work to make your water safe, and let's just be extra careful about the hygiene practices around that water. That safe water.
Katie
Sure, sure. I hadn't thought of it that way. The way, the situation that I've thought of it, I guess mostly related to the UV and the chemical treatment, like say somebody takes their Nalgene and dunks it in the water and then sterilizes it, but they didn't get anything around the rim, like the mouthpiece. And that kind of sounds similar to what you're talking about. Not infected in the same way, like maybe not as much about hygiene and how you're taking care of it, but just the fact that you could forget that not all of the water is in contact with whatever sterilization method you're using and not to just then put your mouth directly on that mouthpiece and just suck up, you know, maybe a mouthful of water that did not get treated by the chemicals or the UV.
Vince
Yeah. I would say in those cases, I mean, again, the relative risk is low, you know, a little bit of water on the lip of a bottle versus the entire one liter that you would then be drinking, right? The relative risk clearly is going to be lower. But you know, I think in all those cases, it's just if you have a concern about it, you're like, "Yeah, logically, that water on the outside, I didn't treat it. You know, I didn't make that safe." So you know, could you use a little bit of your treated water to wipe down, you know, if you've got a paper towel, whatever, you could wipe down the outside. Clearly if you dunked it into something, you could have gotten a little dirt on it, whatever, you know. So I think trying to do something where you've made an attempt to, you know, decrease the contamination potential on the lip of a bottle would make sense. I would feel more comfortable with that with me, but the relative risk is much lower, of course, because you're talking about liters of water you're going to drink in a day, and you definitely want to make sure that water that you're clearly ingesting is made safe.
Katie
Right. I think a lot of this ends up being a relative risk. If you were just scared away by anything that could possibly get you sick, I think you'd have to bubble wrap yourself and stay inside. I'm sure I've gotten many, many mouthfuls of water just being out. Maybe I trip and fall in and I take a mouthful. I've never gotten sick from that. Not that that's a good way to plan when you're thinking about drinking water, but I think it's easy to listen to something like this and then come out feeling like water is out to kill you, and any time you get any of it in your mouth, you're just immediately going to get sick. That's not necessarily the case.
Vince
No, I think that's a really good point too, is you're doing your best. I think have a plan, bring what you can out to make water safe and have a plan there. But be easy on yourself a little bit and not be freaked out about every possible drop of water. Do your best to make water safe. But otherwise, people feel like, "Oh, there's just no way I can remember all of this," or Or, "I can't do it all, so what's the point of doing any of it?" We don't want people to burn out on the messages about what you can do to at least decrease the risk. And so that's really what we want people to do, is to take things seriously, understand what the risks are, do what they can to make it safer. But you're right, go out and enjoy. Enjoy while you're out there in natural world fishing or hiking or whatever it is, and not be all concerned you're gonna get sick the whole time.
Katie
So with that in mind, this is a good way for me to kind of mention my last question, which is if you were going out and say you're going backpacking, I don't know if you're a big hiker, but if you're going out and maybe weight is a concern, so you're not going to be taking a pot to boil and a filter and a this and a that. If you're going out and you want the best safety to weight ratio and the kind of safety to ease ratio, what would you take to feel very confident that your water is safe while also not slaving away just to get one drinkable bottle of water?
Vince
Yeah, you know, I think, I really do, I mean, think that these, the water filters and, you know, kind of, something to disinfect the water. I think disinfecting the water is really pretty important because, again, quite a number of things can actually get through a filter depending on what kind of filter you might have. So I think having something to disinfect the water is pretty important. So whether that's chemical disinfectant, tablets, drops or UV, etc. I think that's really important. However, we just know that you never know what water you might get introduced to or have around you. So the particles, the cloudy water, whatever that might be. So I just think if you can afford it, a water filter plus a disinfectant is the way to go pretty light and you can manage that. But I know a lot of these water filters are not eaten. They can be pretty expensive. So, you know, if that's a barrier to folks, then, you know, just make sure you can bring a water disinfectant that you trust and a container to hold it, you know, that you've got a good plan around how to disinfect your water effectively. That's probably so that you're doing something to improve the water quality and protecting against microbes if there's a barrier to you know kind of these these nice very nice water filters that are out there.
Katie
Okay so it sounds like water purification is kind of the top tier but then if you can also filter it to maybe make it more palatable maybe make it clear or make the purification more effective that would be your way your way to go and if people filter and disinfect you think that's basically a hundred percent you're I mean you're probably not into saying a hundred percent, but you can basically treat it like a hundred percent
Vince
Yeah, no, that's that's the best approach is having a you know that kind of dual approach to water Water treatment, you know filtration plus disinfection is is you know? Yeah, it's about the best most people can do.
Katie
Perfect. Well if folks want to find out more, do you have any resources if people just want to learn more about what's in their water and how to get it cleaned up?
Vince
Well, I'd certainly encourage folks to go to CDC's website. We have a healthy water website. If you search for backcountry water, you'll get to this topic specifically. But CDC, we've got a lot of resources on water treatment, safe water practices, hygiene related to safe water practices. If folks are really interested in reading in more depth, of course, we have scientific publications. There's one that I co-authored with Howard Baker, B-A-K-E-R, in Wilderness Medical Society, Clinical Practice Guidelines for Water Disinfection. And so it's in the Wilderness and Environmental Medicine Journal.
Katie
Oh, that sounds interesting. I don't know how many people have access to that journal.
Vince
Hopefully, it's free online. I don't exactly know, but you know there are various publications that we that we Work on that talk about all these filtration and disinfection proceed, you know processes and things like that so that that's a very long And detailed article that if anybody's academically inclined to really learn more they can do that or just go to our website There's a lot of resources.
Katie
A little something for everybody maybe
Vince
Yes
Katie
All right Vince well I will let you get going I know you've got to cut off soon so I thank you so much for taking the time for this. Hopefully maybe this episode will save somebody from a couple weeks of extreme discomfort in the near future.
Vince
I certainly hope so. Thanks very much.
Katie
All right. Thank you All right guys. Thanks for listening don't forget to head over to the website fish untamed comm for all episodes and show notes and Also, please subscribe on your favorite podcasting app. That'll get my episodes delivered straight to your phone And also if you have not yet, please consider going over to Apple Podcasts and leaving a rating or review. That's very helpful for me, and I'd greatly appreciate it. Other than that, thank you guys again for listening, and I will be back in two weeks. Bye everybody.
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