Water purification and contamination

“http://www.boston.com/dailyglobe2/154/science/Germ


Germs can lurk in water bottles


By Cathryn M. Delude, Globe Correspondent, 6/3/2003

ummer's coming, and thoughts turn to the great outdoors. Before grabbing a water bottle and heading out, think about that bottle and how to keep its contents clean.


Water bottles are not all created equal. Soft plastic bottles bend and crinkle, giving bacteria a place to establish a beachhead, according to Ryan Jordan, a researcher at Montana State University's Center for Biofilm Engineering. Bottles made of hard, unbreakable Lexan plastic don't have that problem. Still, over time, bacteria from your mouth or the environment can grow in any bottle, especially if it contains sweet sports drinks or becomes warm.

No one has actually studied how many people get sick from water bottle bacteria, yet there are ample warnings about water-quality problems encountered by hikers in the back country. All streams and ponds are supposedly contaminated with microbes spread by wildlife, and humans and their animals. These microbes include giardia, fecal bacteria, and cryptosporidium, which cause various gastrointestinal problems such as diarrhea, cramping, and bloating.

To prevent diarrhea on the trail, hikers are warned to use water filters, which strip the microbes from the water, or iodine tablets, which kill many microbes (but not cryptosporidium). These warnings, however, are not based on scientific investigations about the actual risk of water-borne disease in the back country or the effectiveness of water-treatment methods on the trail, according to Jordan.

During the past two years, his research group decided to assess the water quality in streams and lakes at popular recreational areas, such as Yellowstone National Park and the Appalachian Trail, where they could expect to find bacterial contamination because of the numerous hikers. Indeed, they found that gastrointestinal problems are uncomfortably common on the trail. For example, of the 120 hikers who had been on the Appalachian Trail for three months or more that Jordan interviewed for his study, 90 percent had suffered gastrointestinal problems, and 20 percent had problems within the first week.

The prevalence of gastrointestinal infections among hikers might make it seem as though there were high levels of microbes swimming around in back-country water. On the contrary, Jordan found the water had very few microbes swimming about.

But the coating on rocks and sediment at the bottom of streams and ponds, as well as the thin surface film on standing water, did contain the usual suspects. These microbes grew in a slime, which scientists call a biofilm.

If you stir up the sediment or slurp in the surface film while filling your bottle, you gather biofilm clumps with your water. ''If a biofilm clump contains a thousand bacteria,'' Jordan explained, ''there's a much higher chance of getting sick than if you drank the same number of free-floating individual cells.'' By virtue of living together in large, attached groups, bacteria in biofilms become more virulent and resistant to the helpful bacteria in your gut that normally eliminate foreign intruders.

Biofilms can also foil trailside water-treatment efforts. Iodine tablets can't sterilize biofilms, and biofilms clog water filters.

In fact, all the hikers in Jordan's study who had been on the Appalachian Trail for three months or more had experienced filter failure. ''The common perception is that the water filters failed because they were plugged with sediments, and that certainly does happen,'' Jordan said. ''But we found failures even in Montana where we were filtering water from crystal-clear streams all summer. We discovered that the filters' performance degraded because we were filtering bacteria into them, and bacteria were growing biofilms on the filters. Eventually those biofilms plugged up the filters. That's a huge part of filter failure, one that's relatively unknown.''

Currently water filter manufacturers are not regulated, and they safety-test their own products. Because they don't understand biofilms, their tests may not cover the conditions people actually meet in the back country, Jordan said.

For hikers, Jordan recommends these ''best practices.'' To gather water, find a spot where you do not disturb the sediment, submerge your closed water bottle, open it under the surface, and let water flow in from the middle of the water column. Close the bottle underwater and lift it out. That way, you start with biofilm-free water, which you can filter for drinking.

To prevent biofilms from growing on the filter, back-flush the filter every few days to wash out the bacteria. Scrubbing the filter's outer element with a toothbrush is even more effective.

Jordan himself doesn't use filters. He relies on chlorine dioxide drops, which unlike iodine pills can kill giardia and cryptosporidium even in biofilms. (Chlorine dioxide has long been used in municipal water treatment, but is a relatively new product for back-country use.)

Surprisingly, the primary route of intestinal infection on the trail is not water, Jordan said, but rather the link between not washing hands after going to the bathroom, and handling food. He recommends alcohol hand gels rather than soap: ''Soap is too impractical to use properly and alcohol gels kill fecal bacteria more effectively.''

Back-country dishwashing can become very elaborate, but Jordan has these suggestions: Don't wash dishes! Just wipe them clean and dry them out. Bacteria can't live long on a dry surface, and putting them in the sun for an hour will disinfect them. Boiling water for your next freeze-dried meal will sterilize anything that's left in the cooking pot.

All the more time to lie back and enjoy the stars -- or whatever brought you so far from indoor plumbing to begin with.”

“Thanks, Pedxing, I'm going to print that out because that is a subject that I am teaching the girl scouts about this weekend.”

“I sometimes make my own wine and beer and always have sodium bisulfite powder which, mixed with water, is a great steriliser. I rinse out my bottles with it before going on a trip and my teams' water bottles frequently.”

“I heard about this on the news resently- they studied people who reused the same bottle all day long and they even found fecal matter in em even. EWWWW!”

“Can you get sick from someone else who has giardia for instance.

I hike with a guy sometimes who will take water directly from a stream and drink it in his water bottle. He hasn't gotten sick yet, but I know he's going to.”

“I hadn't seen these before... Katadyn Micropur Purification Tablets. The active ingredient is chlorine dioxide.

More water info at the Katadyn site.”

“The water is contaminated if I am near it.”

“IJ, I think the answer to your question is yes, but the vector is pretty disgusting...”

“What's our clearance, Clarence? What's your vector, Victor?”

“Last week, I was fishing on a creek and I came upon an active beaver dam as I fished upstream. I needed to cross the creek so I walked across the dam they built. When I looked into the water on one part of the dam the entire bottom was covered with beaver feces so all the contents would eventually make it's way downstream since it was submerged. Now I know why we filter our water, but even so seeing that doesn't make you too thirsty to drink it.”

“What's our clearance, Clarence? What's your vector, Victor?"
Tilt
02:04:26 PM
06/03/03

roger Roger

ahh a classic.”

“This same topic has been on every outdoor website for the last 10 years.

While it's a good practice to remind people annually, I wonder how much $$ this researcher received for rediscovering common knowledge.

also -- replace your water bottle frequently.”

“Gordon: Actually there a couple of new things in the article - at least that I hadn't seen in the usual articles:

1) That soft plastic bottles that fold and crinkle (vs. Nalgenes) have a greater risk of bacteria colonization.

2) That biofilm is a source of filter clogging.

3) That filters might be improved based on an understaning of bio-films (which have been a hot topic in medicine laterly)

4)That scrubbing the outer element of a filter with a toothbrush will help prevent clogging.

Probably some other things that aren't still kicking around in my head.”

“That previous site was Katadyn.net, not Katadyn. com. Pretty sneaky, eh?

More info on the chlorine dioxide tabs. They are effective against all the nasties (supposedly), without the aftertaste and the temperature restrictions. You may still have to wait some 10-15 minutes --- it doesn't say.

If these perform as advertised, my Pur Hiker can collect some more dust.”

“Our purifier came with instructions on how to run a sanitizing bleach solution through it before storage in between uses. I also usually run the same solution through our hydration systems and dry them thoroughly before storage in between uses.

I don't think we have to worry about biofilms in our stuff.”

“live in balance with our parasites! LOL I volunteered in Africa in a 3rd world nation for a time and I was not the most careful when it came to the H2O. I never had any problems thankfully. My doctor asked me if I wanted to be tested or treated for parasites etc. I declined since I was having no trouble. I told him I was living in balance with them and til one of us was suffering I'd let well enough alone.”

“Btw, I'm much more concerned with sediment clogging my purifier than with a potentioal biofilm clogging it. Mainly because one is so outragiously more likely than the other. Thanks for the heads up though.”

“Oy.
So, how many people out there don't wash their bottles and water bladders? My husband for one. If you ever get stuck in Cherokee, NC, their water is so heavily chlorinated it probably will sterilize your stuff.”

“Bottles get washed, bladders I occaisionally let sit with a chlorine solution in them. Haven't gotten even a tummyache yet.”

“You guys that have abandoned the filters completely for the tabs, what do you do about sediment? Do you have to restrict your water gathering to moving water sources like streams or what?”

“Thanks to this thread, I just spent the last 20 minutes running a chlorine solution through my filter, which I remembered hadn't been cleaned since it's last use.”

“I do the chlorine rinse between trips - but I am wondering now about 2 week long and longer trips.

Maybe I'll switch to tabs. I like being able to get cold water quickly in the summer - but with the weight of a pump and the sanitation issues... I suppose if I left the cholrine dioxide tabs in the water and left the bottle in the spring (to stay cool)...”

“My sister spent 2 years in the Peace Corps in Honduras. She lost some weight there, and kept losing when she got back. Finally, she had to get some more anti-parasite meds before her weight could stabilize at a decent level.”

“Yeah Ped, I've often wondered about those longer trips also. I think maybe I'd pack one of those little squeeze bottles of bleach. I have some really tiny ones that I got in free samples for contact re-wetting solution. They're really handy for stuff like that. It doesn't take much and one of those would probably last a month. Although it might be worth checking out those chlorine dioxide tablets.

There is no such thing as a healthy parasite load.”

“I'd note that the article refers to brushing the contaminated side of the filter, I think, which on a Sweetwater Guardian, is actually the inside of the filter.

I filter, to get rid of the floaters, and treat with bleach, 10 drops per gallon, and never have had any trouble yet. Once the water stands overnight, the chlorine taste is pretty much gone.

Also I filter and treat even in the deep backcountry, because humans aren't the only things contaminating the water. Water only in the Platypus, and a quart of Gatorade in a Nalgene for lunch keep my internal chemistry where it needs to be, even on the hottest days.”

“For example, of the 120 hikers who had been on the Appalachian Trail for three months or more that Jordan interviewed for his study, 90 percent had suffered gastrointestinal problems, and 20 percent had problems within the first week.

Could it possibly be because lots of these hikers never wash their hands and many have bought into the trend of not using toilet paper? Being dirty is one thing but being unsanitary is too much.”

“there's a not-using-toilet-paper trend?? thank goodness i'm not trendy. grooooosssss!”

“Moral of the story is, don't shake hands with any Thru hikers.”

“I met an AT thru-hiker who said he used the really diluted chlorine method. I just stood there dumbfounded when he discussed and as he said, it's what cities do to the drinking water, I thought..... hmmm, makes sense. He said many, many thru-hikers to that. I was so surprised I had never heard of it!”

“It's a lot easier to contaminate water than to purify it.

--Geobeet, 2003”

“Or, as I heard it ages ago, "Add a teaspoon of wine to a barrel of sewage, and you have a barrel of sewage. Add a teaspoon of sewage to a barrel of wine, and you have a barrel of sewage."”

“If Jeffers is gonna read what I post re: water treatment and such..... I will have to keep it real. LOL Don't want any new pages added to THE BOOK. Yessir, I carry the sweetwater guardian and brush it after use. I carry a dropper bottle of chlorine and use it 10 gtts per gallon and I do not ever fail to do so. Dunno what possessed me to make jokes bout living in balance with parasites. Won't happen agin. HOnest.”

“I went on an 11-day trip once to the through Lake Italy in the Sierra Nevada that was sponsored by my university. These "purist backpackers" had a rule against bringing TP. I told them to f-off and brought some anyway. Trying to find something to wipe with above treeline isn't my idea of fun...and neither is a dirty a-hole.”

“sorry to be so graphic! :-0”

“No you're not! :)”

“I trout fish small creeks a lot and I'll wade up a creek for miles fishing it upstream. I think animals contribute quite a bit to spread water born disease. I frequently stumble across dead animals in the water. Last week, it was a dead goose in the water. Deer are common to see too. On top of it animals don't care where they crap and there's plenty near the water's edge from water birds on down the line.”