According to the US Environment Protection Agency (EPA) in 1992, approximately 700 to 900 public water systems used chlorine dioxide to treat potable water. Today, the major uses of chlorine dioxide are:
- Preoxidant to control tastes and odor
- Control of iron and manganese
- Control of hydrogen sulfide and phenolic compounds
Ultralight Backpacking Water Treatment
By Steve K Green
Water is one of the most important items in your pack, and one of the heaviest. You need it to sustain energy. You need it to avoid body aches, headaches, and becoming so uncomfortable that you don’t enjoy your hiking experience.
If you can avoid carrying too much water, you’ll enjoy a far lighter pack. Your ability to find safe water and know how and when to treat it is a valuable skill. Pathogens can sometimes be found in water that seems safe. Much of the water we find outdoors is safe, especially at high elevations and when you’re near the original source. Always consider what is upstream, and err on the side of caution if you don’t know what is above you. Does the water look clear? Don’t worry too much about small animal life in the water. Worry more if there isn’t any life in the water, and ask why.
Some experts talk about running water being safer than still water, but studies have found lake water to be among the cleanest because the ultraviolet rays of the sun kill bacteria near the surface. When taking water from a lake or pond, take water under the surface, but near the surface. Check the rate of water that is flowing into and out of the lake. Are there any stock animals or other animals that could make the water impure?
Much of the response to the threat of Giardia is overkill. A favorite scholarly article on Giardia was written by Robert L. Rockwell, PhD. It’s titled, Giardia Lamblia and Giardiasis, With Particular Attention to the Sierra Nevada. Bob Rockwell is an active mountaineer who made his first trip into the Sierra Nevada in 1952 to climb Mt. Whitney, and he repeats this climb several times annually. He has a bachelor’s degree in Physics from UC-Berkeley, and a PhD in Aeronautical and Astronautical Engineering (Biomechanics) from Stanford.
The article is so good and informative, that its first seven paragraphs are quoted below:
Ask the average outdoors person about Giardia lamblia or giardiasis, and they have certainly heard about it. Almost always, however, they are considerably misinformed about both the organism’s prevalence in wilderness water, and the seriousness of the disease if contracted.
With the advent of the Internet, the amount of information one can easily find on the subject is voluminous. Unfortunately, most of it is flawed in important aspects, being unsubstantiated, anecdotal, or merely quoting other unsubstantiated and anecdotal articles. Official sources, such as many informational publications put out by the US government, are not immune to this criticism.
This paper is the result of a critical distillation of relevant articles, retaining only those from scholarly, peer-reviewed, or otherwise professional and trustworthy sources.
One conclusion of this paper is that you can indeed contract giardiasis on visits to the Sierra Nevada, but it won’t be from the water. So drink freely and confidently: Proper personal hygiene is far more important in avoiding giardiasis than treating the water.
First, an excerpt written by a highly regarded wilderness physician:
“In recent years, frantic alarms about the perils of giardiasis have aroused exaggerated concern about this infestation. Government agencies, particularly the United States Park Service and the National Forest Service, have filtered hundreds of gallons of water from wilderness streams, found one or two organisms (far less than enough to be infective), and erected garish signs proclaiming the water ‘hazardous.”
And another, by researchers who surveyed the health departments in all 50 states and scanned the medical literature looking for evidence that giardiasis is a significant threat to outdoor folk:
Neither health department surveillance nor the medical literature supports the widely held perception that giardiasis is a significant risk to backpackers in the United States. In some respects, this situation resembles (the threat to beachgoers of a) shark attack: an extraordinarily rare event to which the public and press have seemingly devoted inappropriate attention.
The entire article can be found at the web address listed at the beginning of the quote.
Water-borne pathogens are disease-causing bacteria, viruses, and protozoa you can get from impure water. Protozoa are hard-shelled, single-cell parasites, or cysts, that range from 2 to 15 microns in size. The giardia lamblia cyst is one of the most common water-borne parasites in the United States. Cryptosporidium is also a protozoa, and cryptosporidiosis exhibits symptoms similar to giardiasis, including diarrhea, fatigue, fever, weight loss, nausea, and vomiting. Bacteria are smaller than protozoa, and range in size from .2 to 10 microns. They include E. coli and salmonella. Viruses are even smaller at .004 to .1 microns, and carry diseases like hepatitis.
When hiking at lower elevations, you need to be cautious of manmade contamination from agriculture and industry, including herbicides, pesticides, and fertilizers.
No matter what water treatment system you use, be sure your hands are clean, especially after bathroom breaks. This is one of the most important points of this article. Impure hands can often transfer microorganisms to food or water, and the water gets blamed for the result.
Six main methods of purifying your water are available, and there are lightweight options for each.
Boiling is the oldest and most basic way to purify water. A rolling boil will destroy any pathogens. You can kill microorganisms at sustained heat that is less than a boil, but it’s difficult to measure in the field. Make sure the water is actually boiling. A rolling boil is big bubbles that shake the pan, not a few tiny bubbles on the bottom of the pan. To be safe, bring the water to a rolling boil for 3 to 5 minutes. As a general rule, add one minute of boiling time for each 1,000 feet of elevation above sea level. If you’re using the water for cooking, there’s no extra time, fuel weight, or cost involved. But boiling water for drinking is slow and tedious, and adds to the weight of the fuel in your pack. The real weight of boiling water is the weight of the extra fuel you need to carry.
This has been the simplest, most compact, and most cost-effective system for many years. It kills bacteria and many viruses, but not cryptosporidium. Fortunately, cryptosporidium is still quite rare in North American natural water sources. Two tablets are used for each liter or quart of water (32 ounces). A quart is 95% of a liter. If you believe the water to be heavily contaminated, double the dose or contact time. In general, if you are in a hurry, double the chemical dose and halve the contact time. If you want better flavor, halve the dose and double the contact time. For cold water, the tablets take longer to work, so wait for the full recommended time. After adding the tablets to your water, you need to wait up to 30 minutes before you drink. If you rush the waiting time and drink the water, the iodine won’t work to deactivate the pathogens in your stomach.
The most common brand of iodine tablets in the United States is “Potable Aqua.” The bottle has 50 tablets that can treat up to 25 quarts of water. The suggested cost is $6.95. The packaging says “No unpleasant taste,” but most people would strongly disagree, although the taste may bring back pleasant memories of camping as a youth. Even the Potable Aqua brand sells a version of the tablets that come with a second tablet to neutralize the taste. The suggested cost of the combination of iodine tablets and neutralizer is $10.95. This second “PA Plus” tablet that neutralizes the taste, iodine odor, and brown color of the water is simply vitamin C. You need to wait until the iodine has done its work before adding the ascorbic acid tablet. You can crush your own vitamin C and add it to the treated water. Remember to add only enough to make the water clear. Your body can handle extra vitamin C, but too much can lead to diarrhea. After the iodine has done its work, you can also add powdered drinks instead of vitamin C to mask the iodine flavor.
Experts argue over how much iodine is too much for the body. Iodine is essential to thyroid function. It is often added to salt because water and foods are sometimes deficient in iodine. With that said, the Potable Aqua packaging information says, “Not to be used on a continuous basis. For short term or limited emergency use only.” Some literature suggests using iodine tablets for six weeks or less. Although iodine is rapidly metabolized and cleared from the body, you should not use iodine tablets if you have an allergy to iodine, an active thyroid disease, or are pregnant.
Iodine tablets come in a brown bottle to help protect them from large temperature changes. Keeping the tablets dry helps them remain more stable. The tablets will last for up to four years unopened, and seem to work more quickly if they are fresh. They degrade with air, water, or light exposure, but since they are inexpensive, they can easily be replaced every year. The manufacturer of the tablets suggests against switching to a smaller bottle. So, with that warning, if you make the switch, be sure to use a tight, brown bottle that keeps the tablets dry. Even the original cotton in the bottle is meant to absorb any moisture that may be present. If you re-package the tablets to a smaller bottle, try to keep a little of the cotton.
When you treat water in a container with a lid, be sure to let some of the treated water clean the threads of the cap.
Of course, you won’t remove particulate by boiling water, using iodine or chlorine dioxide-based tablets, or ultraviolet light systems. So, if the water looks murky, you may want to start with a pre-filter that’s as simple as a coffee filter or cloth.
The weight of a bottle of iodine tablets is 1.1 ounces. If you purchase the PA Plus that neutralizes the taste and odor, you’ll double the weight. If you re-package the tablets into a one-dram (1/8 oz.) brown bottle, the weight of the bottle is just .2 ounces and will hold 40 tablets, for a total weight of only .3 ounces. If you want to add your own vitamin C and keep the weight down, remember that powders in small ziplock bags can get in the re-sealable closures of the bags and make them difficult to use. You may want to use the smallest, lightest plastic container you can find.
Another iodine treatment is iodine crystals. This product is marketed in the United States under the brand name “Polar Pure.” About 30 small crystals of crystalline iodine come in a 3.2 ounce brown glass bottle. When the bottle is full of water the weight is 4.9 ounces. The suggested retail price is $12.95. You add water to the original small bottle for one hour before putting it in the water that needs to be treated. Of course, this pre-treating can be done as you hike. When you pour from the bottle, the crystals of iodine remain in the bottle. You can treat from 2 to 6 quarts of water at a time. After adding the solution to the water to be treated, wait 20 minutes before drinking.
Water to be treated that is colder than 68 degrees F will take longer. A warmer solution of the original mixture from the bottle will have a higher concentration of iodine. So, fewer capfuls will be required, and more water can be treated before refilling the Polar Pure bottle. You can warm the bottle in your pocket or in sunlight. Dosage instructions, as well as thermal reactive paint on the bottle, tell you how much liquid to pour from the bottle into the water that is to be disinfected.
Pure iodine crystals are stable and slightly soluble in water but evaporate easily. The Polar Pure bottle should be kept filled with water and tightly capped. Water that has been treated should be tightly sealed, too. After the necessary disinfection time, powdered drinks or vitamin C can be added to make the taste more pleasant. Polar Pure has an indefinite shelf life. One bottle treats up to 2,000 quarts of water, so it’s very cost-effective. Some long-distance hikers have used the same bottle for their entire trip.
3. Chlorine dioxide
Another chemical treatment for water is chlorine dioxide. The most common brand is “Aqua Mira.” The lightest version is a package with two one-ounce bottles that have a total weight of 3.1 ounces, including a mixing cap. The suggested retail price is $13.95. This kit will treat up to 30 gallons (120 quarts) of water. The advantages of Aqua Mira are its light weight, low cost, compactness, and good taste, as well as its ability to kill pathogens including cryptosporidium. Chlorine dioxide is used worldwide to treat municipal water supplies, and is known to be an eradicator of bacteria (E-coli, salmonella, legionella), viruses (rolio, rotovirus, hepatitis), and protozoa (giardia and cryptosporidium). The oxidation kills pathogens by breaking down their cell walls. There is no chlorine in Aqua Mira. Even though chlorine dioxide has the word chlorine in its name, the two chemicals have completely different chemical structures. Part A of the kit contains 2% stabilized chlorine dioxide in an aqueous solution, and Part B contains phosphoric acid activator.
To treat a quart of water, you place 7 drops of Part A and 7 drops of Part B in the mixing cap. If the water is cloudy or tinted, use 15 drops of each. You let the mixture react for 5 minutes, and then add it to the quart of water. Shake to mix. Let stand for 15 minutes. If the water is very cold, cloudy, or tinted, let stand for 30 minutes. Some people report a chlorine-like odor. The promotional literature, and some testers, report that the treatment improves the taste of the water. Chlorine dioxide does not discolor water. The kit has a four-year shelf life even after it is opened. Chlorine dioxide is available in tablet form in the Aqua Mira brand as well as some other brands, but takes much longer to use.
Filters can give you treated water quickly, without any chemical taste. They work by trapping pathogens in a microporous screen. Some viruses are too small to trap. Only filters with an iodine matrix are capable of killing all viruses. All filters eventually need cleaning, sometimes in the field. Filter lifetime is determined by the quantity and size of particles in the water. Filters may also clog from the growth of organisms in the filter medium. Some filters can be back flushed. Some can be chemically cleaned. Some need a replacement filter. Ceramic filters can be cleaned and can last a long time, but care must be taken so they don’t break, especially when it’s cold. To qualify as a water purifier, a device has to meet the Environmental Protection Agency standard of removing 99.99 % of all identifiable bacteria, protozoa, and viruses. Finer filters generally mean slower and more difficult pumping.
Filters can be as small and simple as the “McNett/Aqua Mira Emergency Frontier” filter that uses activated carbon to filter up to 20 gallons of water. It is used like a straw, weighs less than an ounce, and retails for around $10. Lightweight “bottle filters” from such companies as “Bota of Boulder,” “H2O On Demand,” and the “Katadyn Exstream” are light at about five to eight ounces, and inexpensive at around $20 to $50. Some list incredibly high microorganism and contaminant removal, including 99.99% removal of giardia and cryptosporidium. Of course, these filters aren’t free flowing. You have to suck to get the water through.
Pump filters include well-known brands like “Timberline,” “Katadyn,” “First Need,” and “MSR/Sweetwater.” They can be as light and inexpensive as the Timberline Eagle at 5.6 ounces and $25. This filter is one of the fastest and works well in water that is not heavy in particulate. The Katadyn Hiker is not the lightest at 11 ounces, but is a favorite because it is so user-friendly. It retails for $60. The Katadyn Mini Ceramic Microfilter is among the lightest at 8 ounces and is known for its quality. The price is $90.
Backpackers like gravity-fed filters because of their obvious advantage of getting filtered water without the pumping. The Katadyn Base Camp weighs 12.1 ounces and has a suggested retail price of $65.
5. Ultraviolet light devices
Ultraviolet light is becoming popular because it’s effective in quickly killing all microorganisms. The ultraviolet light destroys their DNA which prevents them from reproducing. Early models were expensive and didn’t work with a wide variety of water containers, but that’s all changing. The “SteriPEN Adventurer” weighs 3.6 ounces and ships with two CR123 batteries. Rechargeable batteries are also available. Nickel metal hydride batteries are recommended for cold weather use. This style or lithium disposable batteries will give you about 200 treatments. The Adventurer can purify a quart of water in 48 seconds. The cost is $129.95.
The “mUV water purifier,” or “AquaBobber,” from Meridian Design, Inc. weighs 2.4 ounces and costs $49.99. It operates with an internal battery that can be recharged by attaching its magnetically connectable leads to almost any external battery including AAA, AA, C, and D sizes. The device floats and can be inserted into almost any container, including a standard water bottle opening. A quart of water can be treated in 90 seconds. You can perform 20 treatments per charge.
Agitate the water gently, until the light tells you it’s done. UV purifiers don’t work in murky water, so if that’s the only water you have, you’ll have to pre-filter it until it’s not cloudy. You also need to make sure you don’t drop a UV device.
6. Sodium hypochlorite (Household bleach)
A large number of agencies, including the Red Cross, tell you that ordinary bleach, such as Clorox or Purex can treat water in emergencies. The Clorox website lists these instructions:
“Disinfection of Drinking Water (Potable)
When boiling of water for 1 minute is not practical, water can be made potable by using this product. Prior to addition of this product, remove all suspended material by filtration or by allowing it to settle to the bottom. Decant the clarified contaminated water to a clean container and add 8 drops of this product to 1 gallon of water (2 drops to 1 quart). Allow the treated water to stand for 30 minutes. Properly treated water should have a slight chlorine odor. If not, repeat dosage and allow the water to stand an additional 15 minutes. The treated water can then be made palatable by pouring it between clean containers several times. For cloudy water, use 16 drops of this product per gallon of water (4 drops to one quart). If no chlorine odor is apparent after 30 minutes, repeat dosage and wait an additional 15 minutes.”
The dosage listed is for treated city water, so lake and stream water will likely need the higher amounts. Use only liquid bleach that contains 5.25% to 6% sodium hypochlorite and doesn’t have any perfumes, dyes, or other additives. Be sure to read the label. Treating with bleach should be thought of as an emergency method. Although countless websites list this method of treatment, they do not show data for effectiveness against giardia, cryptosporidium, and other pathogens. And these sources do not list the effects of long-term use on the body.
There is an abundance of information about water treatment from the Environmental Protection Agency and the Centers for Disease Control.
Now you’re equipped with a wide variety of water treatment options. Your region and style of camping will tell you what water treatment is right for you. Hike light. Have fun.
About the author: Steve Green of http://www.hikelight.com is an avid hiker who has enjoyed trimming his backpack weight for over 40 years.
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