Water Purification Systems

Experience From - Ed Furtaw , Bryan Spellczech , Matt Mahoney , Dan Baglione , Martin Hillyer , Brick Robbins#1 , Dave Scudden , Brick Robbins#2 , Al Zeller , Earl Blewett , John Medinger , Howard Breinan , Mike Erickson , Mike Riggs , Doug McKeever , Rich Schick , Shannon Lyons , Michael Dorovitsine ,

Ed Furtaw

Joel wrote:

"I am trying to get all my equipment ready for Hardrock now; I've never had to rely on stream water before to drink, but since it may take us four or five hours to get from one aid station to the next there, supplemental water will be a necessity.....I've bought one of those Oasis drinking bottle/water filter gizmos, and some Aqua Pure iodine- based purification tablets, and I don't know if I can/should rely on the Oasis and hold the tablets as backup or use both in combo or what....if you have a tried and true method for getting palatable and drinkable water up in the mountains from what is there, i.e, ground water and snow, while you are running or fast-packing, let us know..."

I have not used an Oasis bottle, but I have successfully used Aqua Pure iodine tablets to treat water at the Barkley Marathons. The water I treated and subsequently drank was from a spring and had some dirt in it. I waited about half an hour to drink it after treating it. It tasted like iodine, but I didn't get sick, and went on to finish Barkley (55 miles) that year (1988), thus becoming the first-ever official finisher at Barkley.

The various sections of Barkley between water-drop locations routinely take me between about 2.5 and 5 hours. I normally carry three 29-ounce bottles, and that is usually enough for up to five hours for me (assuming it's not too hot). The one time I used the iodine tablets was because there was no treated water available at one of the water-drop locations.So I wonder if you would really need to treat water at Hardrock; you might be able to carry three bottles and get safely between stations even up to five hours apart.

What do most Hardrock runners do?

Bryan Spellczech(?)

"Supplemental water will be a necessity.....I've bought one of those Oasis drinking bottle/water filter gizmos, if you have a tried and true method for getting palatable and drinkable water up in the mountains from what is there, i.e, ground water and snow, while you are running or fast-packing, let us know..."
I have a tried-and-true method. It's called the Oasis water bottle ;-) Carry two, been very happy. Work like a charm. What else is there to know? I didn't get sick yet (well, besides wanting to run ultras all the time :-)).

I even talked one of my roommates into buying one for hunting/camping (they're light weight, take up only the room for the bottle [ie. don't need bottle *and* filter], and cost less to replace than a new filter for a pump). No complaints so far. A little track work, a little trail running...all in all a very nice day (70 and sunny).

Matt Mahoney

Joel wrote:

"I've bought one of those Oasis drinking bottle/water filter gizmos, and some Aqua Pure iodine based purification tablets, and I don't know if I can/should rely on the Oasis and hold the tablets as backup or use both in combo or what."

It would probably be a good idea to carry the tablets just in case. The bottle of tablets is small. I've used them at Leadville and Barkley and when hiking in the Rockies, and I plan to use them at Laural Highlands this weekend. The directions say to add one tablet per quart or liter, or two if the water is dirty, wait 3 minutes, shake, let a little water leak out to wet the threads around the cap, and wait 10 more minutes. I usually put one tablet per 20 oz. bottle and assume that running with it shakes it up enough.

I drink from one bottle while waiting for the other one to dissolve. It adds a slight chlorine taste but you get used to it. You could probably take your chances and drink untreated water (which I've done sometimes). I think its less likely to have giardia if it's close to the source, like melting snow at high altitude, and besides, giardia won't kill you.

Dan Baglione

I bought the Oasis and, even after cutting the spout, decided it required more effort to draw water through the filter than I am willing to expend. The filter also reduces the amount of water in one bottle. While the sun is more intense, the temperatures are generally cooler at 11000' although some of those climbs in the sun can get warm. In 4 training runs and in 28 miles of the race in 1994, I had enough liquid to last between aid stations. I did tank up at aid stations. I have no problem with iodine tablets, especially the newer ones which are combined with something to remove or diminish the iodine taste.

Martin Hillyer

Ed wrote:

"Joel, I have not used an Oasis bottle, but I have successfully used Aqua Pure iodine tablets to treat water at the Barkley Marathons. The water I treated and subsequently drank was from a spring and had some dirt in it. I waited about half an hour to drink it after treating it. It tasted like iodine, but I didn't get sick, and went on to finish Barkley (55 miles) that year (1988), thus becoming the first-ever official finisher at Barkley."

The latest time I bought AquaPure at REI it came with a second bottle of pills which killed the iodine flavor (you still have to wait the time for the iodine to work). Worked perfectly!!

Brick Robbins #1

Here is a copy of a post about water filters I wrote for the PCT Mailing list, so it mentions some specific places, and backpacking. All the info should apply to the UltraRunner also. I've done a bunch of research on this stuff preparing a web page for the PCT Association. If you find anything wrong with the info posted here (I know there are lots of extremely qualified folks on this list) please let me know. If anyone want the "next installment" please e-mail me, as I don't want to clutter the list.

Here is a synopsis of the info:


There has been considerable discussion of late on this list about water filters, and for the hiker to make a good choice, he/she must know a fair amount about water quality along the trail, and potential hazards.

There are two types of hazards in water along the PCT: biological, and chemical.

This hazard comes mostly from human pollution, and is a bigger problem near civilization where you are more likely to be able to use a municipal water system. There are some notable exceptions, like Chimney Peak Campground, which has water contaminated by a heavy metal (uranium). Most filters will not remove ANY chemical contaminate. The exception are those that have a charcoal cartridge, which will remove some volatile chemicals. (The level of uranium at Chimney Peak won't bother you if you only drink it for a short time, but the Host at that campground drinks bottles water...Also the problem is heavy metal poisoning, not radiation!

This hazard is divided into 3 types of "germs" -- cystic protozoans like Giardia, bacteria like E. Coli, and viruses like Polio and Hepatitis.

VIRUSES AND BACTERIA are small and difficult to filter out, but fortunately they are not a much of a problem in the surface water in the USA. There may be a low level of some bacteria in the water, but the normal immune system should handle them. Even in prepared foods, the FDA has established "acceptable" levels of coliform bacteria (read: fecal matter). People with impaired immune systems and the very old and very young may have problems, but they probably won't be out on the trail anyway.

Bacteria come as small as 0.2 microns, so you need a filter size at least 0.1 microns or smaller to filter them out. The smaller the pore size, the more difficult the pumping, and the quicker it clogs. Viruses cannot be filtered out, and require chemical treatment, such as that provided by iodine matrixes found in some filters. If you are worried about viruses, the two most common water borne are Polio and Hepatitis. There are vaccines for both.

CYSTS are the real problem for the PCT hiker, with the big villain being Giardia Lamblia and to a lesser extent, Cryptosporidium Parvum. These are intestinal parasites, that can only multiply inside a host. They enter the water from feces from an infected animal or person. As far as I can tell from my research, only omnivores such as humans, beavers, bears, marmots can be infected. Deer, cows and horses don't seem to carry this bug, so as unpleasant as a cow polluted spring is, you won't get Giardia from the cows. Cysts can't multiply in the water, so there has to be an infected animal or person upstream for there to be a hazard. Even though the powers that be warn you to treat the water, very few of the streams are infected. If you ask the back country rangers in Sequoia-Kings National Park if you should filter your water they will say "yes" loudly. If you ask them if they filter theirs, they will say "no" quietly.

When these germs leave the body, they encyst themselves (cover themselves with a tough coating) that makes them extremely difficult to kill chemically. The FDA has warned cities that use surface water that normal chlorination WILL NOT KILL GIARDIA. For the backpacker, this means that chemical purification may not work, depending on the type and concentration of the chemicals used. Iodine seems to be the best, but it may still take SEVERAL HOURS to kill the giardia if the water is cold. Chlorine tablets are even worse.

Fortunately, cysts are fairly large (5 microns) and are easy to filter out. A filter with a pore size of 2 microns or less will work fine. This means that a fairly cheap, easy pumping filter will protect you from giardia just as well as an expensive slow pumping filter.


I have seen folks who buy the heaviest and most expensive filter in the store, with charcoal, and iodine matrixes and 0.1 pore size (that would be OK to use in India) and then wrap the inlet hose along side the outlet hose and stuff the whole dripping pump into a soggy stuff sack.

They wonder later why the hi-tech filter didn't keep them from getting sick...

If you want to keep the pump effective, you need to take care not to contaminate the filter outlet hose with unfiltered water from the inlet side of the device. I haven't figured out an elegant way to do this yet. Any suggestions would be welcome.

For more info on water purity and treatment, I recommend the Oasis Water Filter/Bottle page. It is a product that is not suitable for overnight backpacks, so this is not a sales pitch. It does have descriptions of and links to several water purity-microorganism topics. It also has some neat pics of Giardia, and other bugs.

The UR.. is http://www.dimensional.com/~zakoasis

In the next installment, I will discuss the effects of and treatments for Giardia and my own person feelings about back country water.

Dave Scudden

I always carry a little baggie with half a dozen iodine pills to purify stream water. The additional pills for killing the iodine taste are nothing but vitamin C: 28 mg each. I buy the iodine pills without the neutralizer (cheaper) and throw in a few regular vitamin C pills. After waiting the requisite 20 minutes to let the iodine do its stuff I crumble a bit of a C into the bottle and presto, the iodine color and taste are gone. No need to worry about OD'ing on the C either.

One fun aspect of using iodine is that if your bottle has anything with starch in it, it will turn the water a brilliant blue.

Brick Robbins #2

In my opinion all the posts saying "I put potable aqua in my water bottle, shake and wait for 10 minutes and I never got sick" are more a testament to the rarity of Giardia in surface water than to the efficacy of Iodine for killing Cysts. It also might reflect the fact that most ultra runners are healthy adults with good immune systems.

Iodine will kill bacteria and viruses that fast, but from all the research available out there, it just takes longer than that to kill Giardia (depending on the water temperature).

I personally think that the whole Giardia/back country water scare is blown WAY out of proportion by lawyers and water filter salesmen. Some streams are infected, but not many. The closer you are to concentrations of people, the more likely the infections.

A recent study found Giardia on table tops in 40% of day care centers studied. You are most likely to get Giardia if you have an infant wearing diapers, not from a back country stream. If you do get infected, it is likely that you will have few or no symptoms, depending on you immune system. Then again you could get quite sick also.

Those of you that obsess about cleanliness, worry about germs, and carry pepper spray to protect yourself from cougars (but happily run on the roads beside speeding cars) I encourage to disregard the research, and chemically treat, then boil, then filter your water. By the way the biggest outbreaks of disease from cysts have come from municipal water systems, so you better follow the same precautions with your tap water.

Al Zeller

Please be advised that giardia does exist - it isn't fiction. After drinking from the little streams at the start of the climb up Devil's Thumb at WS three different years with no problem, I got giardia two years ago from one of them. At least one other person had a similar experience. So while it isn't dehibilitating, being on the run so much isn't a lot of fun. I think I'll use iodine or filter bottle at Hardrock this year.

I will admit, however, that given the choice between getting dehydrated and dropping out of a race or getting giardia two weeks later - I'd always opt for the water.

Earl Blewett

I really have to agree with Brick Robbins on his post about the usefulness of iodine against Giardia cysts. Until I moved to the states I spent time in northern Saskatchewan each summer. During canoe trips we always drank the water straight out of the lake. We were careful not to drink in the vicinity of Indian reservations, permanent human habitats are the places to worry about the cysts.

FYI I've also had Giardia a couple of times, probably because until 16 I spent every summer or my life up north. However, the last time I got it we had passed through an area that was going through a giardia epidemic but my canoeing partner had no apparent symptoms, and I only knew I had it because I bloated up with gas and had discomfort when running past 40 minutes. That and blood in my stool. The clinic couldn't isolate any cysts, the usual story, and I didn't want to bother with an endoscopy. The symptoms passed a in few weeks. However, a friend of mine had terrible diarrhea and GI tract damate from Giardia, but she was in her early 70's at the time.

If you want to spend the big bucks for filter don't do it for giardia.

John Medinger

Anstr wrote:

"Has anyone done any research, i.e. taken water samples from a random sample of streams and lakes in the Sierras and tested for Giardia? How many people actually get sick from drinking ground water in the woods? A little bit of actual data might be helpful here."

At least as far as the Western States trail goes:

Howard Breinan

Just a caution for those of you that use iodine:

I have seen in several written sources that iodine tablets will degrade over time due to contact with moisture. The recommendation for backpackers is to throw the bottle away and get a new one every time you come back from a trip. However, I have NOT seen any discussion over how much moisture does damage and how long it takes to reduce the iodine's effectiveness. Anybody else heard this?

Bottom line: plastic bag storage is not a safe way to store the iodine long-term, and may or may not be safe for the short term. Most bottles come with a piece of cotton or some other desiccant to protect the pills in their original container. Just one more thing to worry about if you have giradiphobia.

Mike Erickson

Help me out here folks. I'm told that if your are using a filter-in-bottle hydration system, and you pretreat the water with iodine tabs, you can ruin your filter. In other words, the filter by itself is OK, and iodine by itself is generally OK...but don't mix the two. Truth? Fiction? Fantasy?

Mike Riggs

Here's the Pur FAQ.

I have this model and haven't gotten sick yet on a couple of hikes. If you use a microfilter then you shouldn't need iodine but I suppose you could put some in the bottle after you filter it.


Mike Erickson #2

Mike, thanks for the response. I understand how filters have generally replaced chemical treatment as the H2O cleanup of choice for wilderness travellers and own a couple myself. My issue is this: I want to be able to run unsupported for extended periods in locales where water sources are sporadic at best. In other words, multiple bottles. I see the system as 3 bottles; one in hand with built-in filter for immediate need and two in my beltpack, iodine treated for use after the first runs out. Here comes my original question, it's inevitable that I'll get the bottles mixed up and as a result try to run the treated water through the filter; again, will this damage the filter elements?

This is probably a lot of hullaballu about nothing. 'Drink the water

Doug McKeever

So far as I know, the iodine is a disinfectant which handles things like viruses which are too small to be filtered, and the filter mechanically blocks stuff like amoeba, dirt, and larger bacteria. Here in the northwest a filter is usually sufficient. Some companies sell units which both filter and disinfect, but contact time with the iodine resin is critical. This requires an incredibly slow pumping time, at a rate of about one tablespoon per minute, in order for the iodine to do the job! Pump faster and you have only the illusion of treated water.

If you put iodine such as Potable Aqua in the bottle in which you have your in-bottle filter, you shouldn't have a problem if the iodine is thoroughly dissolved. However, if the iodine is not dissolved but rather is in suspended micro-particles, then the issue of those particles clogging the filter is real. I don't know for sure whether Potable Aqua (a very common iodine tablet) is dissolved or simply broken down in water into small particles. I should think that filtering the water with a filter capable of removing stuff down to 2 microns should give you a large measure of safety in the U.S.

Chemical treatment should not be necessary.

If you do treat the water chemically, be sure to allow sufficient time for the substance to react thoroughly with all the bad critters in the water....usually 10 minutes minimum but 20 for very cold water. Also, don't put a flavoring containing citric acid in the treated water until the minimum time has passed. The acid will neutralize the effects of the iodine. One final comment is that Potable Aqua (mentioned only because I am familiar with it) has a shelf life of about two years. This used to be printed on the label but appears to no longer be given. Old tablets may give only the illusion of treated water.

Rich Schick

For most purposes I think iodine or chlorine will suffice. If you are going to be drinking really funky water, iodine probably has a slight edge. Literally it is for the most part a matter of taste. I personally prefer the taste of chlorine, so I use three drops of Clorox bleach per 20 oz bottle, if I just can't wait to drink I double the Clorox and shorten the wait time which normally should be 20 - 30 minutes. If I'm that thirsty who cares what the stuff tastes like!

With both iodine and chlorine there are some questions about toxicity with long term use. Seems like chlorine increases the risk of bladder cancer slightly, and iodine can mess up your thyroid. A couple days here or there probably isn't a big deal. If I used either weekly or more, I guess I would switch to iodine.

Either system is effective, dirt cheap, and adds virtually no weight to your gear. Below is a "how to" for ultra cheap iodine treatment, same system is also good with Clorox.

"My own preference is to use Betadine® (10% povidone-iodine) in a small dropper bottle, and a one liter nalgene bottle. I fill up the bottle from a stream, drop in 4 drops of Betadine®, screw on the lid, and put it in my pack. Half an hour later, it is ready to drink. With minimal planning ahead, I rarely need water faster than this. I like this system because I carry Betadine® in my first aid kit anyway, and I personally think the flavor is less noxious than some other forms of iodine. I don't usually feel the need to add flavor crystals to my water, rather I joke that iodine is "the taste of safety." A little goes a long way: 30 ml of Betadine® is enough to disinfect 150 liters of water, or drinking water for about 50 days of active trekking (I am presuming that some additional fluid intake exists from tea, soup, meals, etc.)."

Shannon Lyons

I vote to drink the water too. Also, a preventative measure no one mentions is to take Flagyl before, during and a little after the event of drinking untreated water. It does the trick.

Michael Dorovitsine

I found one with both - from PentaPure.