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How To Purify Water - A Complete Overview

Updated on May 2, 2016

Learning How To Purify Water Is Essential

Learning how to purify water should be important to everyone because safe drinking water is essential for life. In this article you'll learn all of the purification methods that you can use in a variety of situations to render water safe for use. Bookmark and share it now, it's a comprehensive guide.

There are precious few things more important than making sure you and your family have adequate and safe camp water when you're outdoors, or that you have the ability to purify plenty of drinking water for hiking trips; this goes without saying for those on longer, multi-day backpacking trips. But this brings up the common question of how best to provide for safe drinking water in all of these situations, and the opinions on this vary greatly.

For me the answer is simple...pick whatever purification system suits you (your budget, your pack space, weight tolerance, etc...) and learn how to use it properly, and have a back up or two at all times. Almost all of the top systems used by hikers and campers work well so browse over the reviews, pick one that suits your style and preference, and go with it... it's not something to fret over too much as long as you're using a tried and true system. On our backpacking trips we take a Katadyn Hiker Pro for camp water needs or major resupplies, a Steripen Adventurer for quick refills of water for hiking during the day, and every member of the party carries water purification tablets as a backup in case the party gets split up. Also, different people carry the Steripen and Hiker Pro. Granted we're mostly hiking high in the Colorado Rockies, and the source water may be much more questionable where you go, and that's why it's important to look at all the systems and pick the ones that will work best for you.

Below we'll discuss the major purification systems used by hikers and campers, and then highlight their strengths and weakness and hopefully provide you with enough information to help you reach an informed decision that also gives you confidence taking your chosen product into the field. Having gone through the learning process and product hunt myself, I understand your concerns that you and your hiking party have plenty of safe drinking water, so the hoopla over how to purify water and the various systems is quite justifiable.

Did You Know...

The U.S. Environmental Protection Agency reports that 90 percent of the world's water is contaminated in some way.

Types of Water Purification Systems

How You Purify Water Matters

To start the discussion it's important to know that there are essentially 4 ways you can make water safe for drinking, and which one(s) you use depends on your personal preference (can you tolerate a chemical aftertaste) and your circumstances. But in fairness no one uses chemical treatment as their primary source for disinfecting water, it's meant to be a backup method in most cases. Regardless, having a basic understanding of how to purify water (the primary methods used to render camp water safe) is important.

1) Boiling Water

This is the most certain way of killing all microorganisms. According to the Wilderness Medical Society, when the water temperature rises above 160° F (70° C) it will kill all pathogens within 30 minutes and at temperatures above 185° F (85° C) it kills them within a few minutes. Therefore, by the time water reaches its boiling point of 212° F (100° C) all pathogens will have been killed. Here's what the CDC says in a publication titled "Water Disinfection for Travelers":

"Although boiling is not necessary to kill common intestinal pathogens, it is the only easily recognizable point that doesn't require a thermometer. All organisms except bacterial spores, which are not usually waterborne enteric pathogens, are killed in seconds at boiling temperature. Therefore, any water that is boiled for 1 minute (to allow for a margin of safety) should be adequately disinfected. Because the boiling point decreases with increasing altitude, water should be boiled for 3 minutes at altitudes above 6,562 ft (2,000 m). To conserve fuel, the same results can be obtained by bringing water to a boil and then turning off the stove but keeping the container covered for several minutes."

The benefit of boiling water is that you can rest assured that almost anything nasty you were afraid of has been killed. Another good thing is that you don't need chemicals or supplies... as long as you have access to water and have a fire, you can treat it. And of course if you're using the water to cook a meal you'll be boiling it anyway so it becomes a no-brainer to not treat the water another way first.

The drawback of boiling water is obvious, you need a fire and a container. So that means it's not a quick fix or something to be done on the go. That is, unless you're packing a Jetboil or similar quick boil cooking system, in which case boiling water is a few minute ordeal. Boiling water can be made more palatable if you filter or strain the water to remove larger particles (unless you just don't mind floaters), and boiled water will most often retain the smell and taste of the source water; if we're talking sludge pond then this smell and taste could be objectionable to some. As a life or death method then of course that won't matter, but for hikers and campers planning on their backup method of treating water it's worth mentioning.


2) Chemical Purification

This is an effective means of rendering camp water safe for consumption and is an ideal backup to ensure you have safe water for hiking and backpacking trips, and takes up very little space. However, Chemical Purification has some important caveats. First, since it's a chemical base the active ingredients can break down over time, reducing the effectiveness of the treatment, and because of this expiration dates for chemical treatments are necessarily important.

The other is that (once again because it's a chemical base) the directions on the packaging must be carefully followed because concentrations of the active ingredient could be different, and because the treatment varies based on the water temperature, cloudiness, pH balance, etc... always be sure and follow the directions so that you don't become ill while trying to make your camp water safe. Also note that if the water temperature is below 40° F you need to double the treatment time since it takes much longer for the chemical agent to act in colder temperatures.

There are two basic chemical treatments that you'll come across; Chlorine based water treatments and Iodine treatments. It's important to know if anyone in your camp or party has an allergy to iodine because the water treated with it can be deadly for those with an Iodine allergy (some people allergic to Shellfish are also reactive to Iodine).

Iodine Treatments

There are several commercial brands available (see reviews below) and it's a good idea to go with them since the packages contain instructions for use. However, you can also purchase 2% Tincture of Iodine and add 5 drops per quart for clear water and 10 drops per quart for water that is cloudy.

Chlorine Treatments

If boiling is not possible and you have no other means to prepare camp water, treat the water by adding liquid household bleach, such as Clorox or Purex, by adding 3 - 4 drops per liter (quart) for clear water, or add 4 - 5 drops for cloudy water or in colder temperatures. Household bleach is typically between 5 percent and 6 percent chlorine, but be sure to not use any bleach that contains dyes, perfumes or other additives. Swirl the mixture and let it stand for 30 minutes (60 minutes if the water is cloudy or the temperature is below 40° F). There are also commercial products available which are reviewed below.

The advantage to chemical treatments is that you can grab some water, drop in the tablets or droplets, and forget about it for a while until it's time to drink. It's a relatively effective treatment for no more fuss than is involved, and they pack really well for backup water for hiking and backpacking.

The disadvantage is that 1) chemicals have a shelf life, after which they lose their effectiveness. 2) Chemicals leave a taste in the water that some find really objectionable. 3) They don't kill "everything."

3) Filtration Systems

These devices can use a variety of mechanism to feed the water through a filter system, such as a mechanical pump or gravity feed bags. Water filtration systems are great for providing safe camp water and I've always relied on them for my water for hiking because I prefer to not use chemicals unless I have to, and I dislike the after taste of chemical treatments. See the product reviews below, but the essential difference between the various systems involves the size of the particles they are able to capture; the best systems can remove organisms down to 0.2 microns. See the note below about the difference between a "filter" and purifier." The latter adds additional elements beyond simple filtration, which can include any combination of charcoal, ceramic, iodine or silver treatments.

The advantage to Filtration Systems is that they remove particulates (floaters) and often remove smell and taste depending on the model. And if it's a purifier then it removes almost everything you would be concerned about, and does an even better job of removing smell and taste from the source water. Most of them are relatively quick and easy to use... dip one end into the source water, the other in your storage bottle and start pumping, drink and repeat. There is no waiting for the water to cool or the chemicals to react, as in other methods.

Some of the disadvantages are 1) you have to be careful not to damage the unit or cartridge while hiking and backpacking. If you damage it you may be using your backup. 2) The purification units can clog if you don't use care when getting the water from source. 3) Most units require both hands... if you're injured it could be problematic to filter the water.

4) Ultraviolet (UV) Treatment Systems

These are really great because they leave no after taste, and according to the Center for Disease Control (CDC) they kill all waterborne pathogens, and extra doses of UV can be used for added assurance and with no side effects, unlike Chemical Treatments. The notable drawbacks include the fact that these do not remove bad tastes from water (think pond water), or particles, and the water must be clear since the treatment requires the penetration of UV light. Also, according to the CDC's website it's difficult to know if the devices are delivering the required UV doses. And there's no persistent residual concentration like you would find with chemicals so doesn't prevent re-contamination during storage.

UV devices have a huge advantage... they are the simplest and quickest to use. Add water to your container, swirl the wand for 45 seconds or so, and drink safely. They are also amazingly effective at killing the baddies. But as noted above, the disadvantages are there, which also include a fragile unit that you have to be careful not to damage, and they all have a definite battery life after which they're useless unless you have more batteries or a recharge station.

Ultraviolet (UV) Treatment Systems - SteriPen Freedom Shown
Ultraviolet (UV) Treatment Systems - SteriPen Freedom Shown

You can improve the taste of camp water by crushing and adding a Vitamin C tablet to treated bottles. You can also pack flavor packets for water when hiking, specifically for this reason. I always take Emergen-C Vitamin C Drink Mixes on backpacking trips and they work well for treated water.

Available at Amazon and many stores
Available at Amazon and many stores

Emergen-C Vitamin C Fizzy Drink Mix

I love these- they're compact for backpacking, they mask bad tastes from source water, and they:

- Have a powerful blend of Vitamin C,24 nutrients,7 B vitamins,antioxidants, and electrolytes

- Support the immune system and increases metabolic functions

- Enhance energy levels

I take these on every single backpacking trip and have one daily.

Regardless of the situation (military, hiking, camping, etc...) have you ever used a Chemical Treatment like we've talked about on this lens to treat your camp water?

Have you ever used Chemicals to render water safe for drinking?

See results

Purifiers Are Top Choice For Camp Water Treatment

And Its How Most Hikers Purify Water On The Trail

There are other methods to render camp water safe, but they aren't mainstream methods and some require time and materials hikers and campers may not have access to. Read all options at Wikipedia's site about portable water purification. However, one method worth mentioning here is SODIS, or Solar Water Disinfection. It essentially involves using the UV power of the sun to kill pathogenic organisms in the water.

You place your mostly clear water (filter it in clothing if necessary to get it mostly clear) into a clear PET (Polyethylene terephthalate) bottle, 2 liter size or smaller, and remove the labels and any dirt or debris. Fill it only 2/3 full and shake vigorously for 30 seconds to improve oxygenation of the water, and then fill the rest of the way. Then let the bottles rest in full sunlight. If the sky is less than 50% cloudy the water can be consumed in 6 hours. If the sky is mostly cloudy it takes two full days to disinfect the water. Here's a great article in pdf form where you can read more about SODIS.

Back to the topic of this leans, the best way to purify water...

... for me the clear top choice of a primary water treatment method is water purifiers because while I do own and love my SteriPen, I don't trust the fragile unit as my sole or primary (plus there's the question of needing charged batteries) and I prefer the way the filters remove floaters, smell and taste. And while "I" prefer and use the Katadyn Hiker Pro, any one the top brands will work so go with what you like and learn how to use, clean and protect it, and enjoy your safe camp water.

It's also worth noting that there IS a difference between water "purification" systems and water "filters" - the distinction matters a lot if you're relying on your system entirely for your camp water or as your primary source of water for hiking in remote locations.

Most water filters remove bacteria, protozoa and parasites, but few, if any, viruses. They also, of course, "filter" out sediment and some elements that might contribute to a bad taste.

Water purifiers, however, are the top choice for campers and backpackers because they remove not only bacteria, protozoa and parasites, but also some viruses which can be more than just nasty, even deadly. Higher end purifiers have a smaller pore size and therefore filter out more. Here's a link to the EPA Guide Standard for testing water purifiers.

It's interesting to see claims by some that such and such purifier "removes some viruses" and that other do not, as if the difference was some miracle technology. The whole point of these filtration systems is the pore size to which they effectively trap particles. If a virus is .2 microns or larger then a .2 micron filter essentially removes that virus. To make it clear, the problem is that some viruses are really small and will easily slip through most of these portable filtration systems. It's not something to get overly concerned about in the U.S.; my Hiker PRO only filters out to .2 microns and I've never worried about it because its mostly the bacteria and other baddies I'm worried about here, which the .2 microns size works great for.

Did You Know...

Each year 3.575 Million people die worldwide from a water related disease? That's equal to the entire city of Los Angeles.

Boiling Camp Water - The Essential Jetboil

The Surest Way I Know How To Purify Water And Cook Meals

Depending on the size of your camp or hiking party you may be able to keep your gear simple and light. For several years I have used the Jetboil Flash Personal Cooking System (PCS) and it has worked fine as the sole cooking source for 3 of us. It is very light, and incredibly reliable... oh, and FAST. It boils 1/2 liter of water in 2 minutes, 3 at higher elevations. Whether you are considering this as a backup to boil questionable water or as your primary cooking source, this is simply the one piece of gear every camper and backpacker should have. The Jetboil has a nearly 5 star rating on Amazon... it is that good. Did I mention it's a fuel mizer, too! This thing sips fuel saving you the weight of added containers.

Because I prefer to pack with Oatmeal and freeze dried meals, this is really all I need for meals, coffee, and to disinfect camp water if needed. We bought an extra Companion Cup so we can keep one boiling at all times while preparing meals and drinks.

Jetboil Flash With Java Kit - Amazing Gear!
Jetboil Flash With Java Kit - Amazing Gear!

Did I Say How Much I LOVE My Jetboil

Top Choice For Iodine Water Treatment

This is one of the top rated Iodine Treatment products and is a great option to take along as a backup for camp water. While some people dislike the taste left behind with Iodine treated water (and some people might be allergic as noted earlier), in general this is a reliable backup, although it should be noted that many sources cite Chlorination as a better alternative to Iodine treatments.

Having been in the military I've used Iodine in the past and I have to say it's my least favorite in terms of the taste it leaves in the water. But like many backup and emergency supplies, it serves the intended purpose if you need it. These Iodine treatments can be stored for up to 4 years in optimum conditions and retain potency.

The Top Choice For Chlorine Based Water Treatment

Potable Aqua's Chlorine Tablets are proven effective against bacteria, Giardia, Lamblia, Crystosporidium, and viruses. Leaves little to no aftertaste, in fact it improves the taste and odor of questionable source water.

Despite my mention of little to no aftertaste I find that it does leave a noticeable chlorine smell and slight taste, but as others note it's much more preferable (to me, too) over Iodine treatments, and of all the chlorine tablets I've used these are among my favorite, by far.

It takes about 4 hours to effectively treat water, but it's worth the trade off when it comes to being very sick.

How To Purify Water Reliably For Hiking and Camping

Water Purifiers Absolutely Steal The Show

I haven't met a backpacker on the trail yet who doesn't pack a water filter for purifying their water. And while the manufacturers and models vary greatly, most campers and hikers agree that these purifiers are the way to go. I have personally used and relied on the Katadyn Hiker PRO. I like its small size and large volume of output (1 liter per minute). I also like that I can trust it to remove virtually everything from the source water, and thanks to the activated carbon insert it also removes virtually all taste and odor... water from a lake that smelled somewhat fishy, tasted and looked like tap water after being filtered through this unit. The filtration system is rated to 0.3 microns. And with the included adapters filling large mouth Nalgene bottles or the fitting in the smaller openings that some hydration bladders have is no problem. The Hiker PRO has a 4.2 (out of 5) star rating based on 78 customer reviews.

The much pricier Katadyn Pocket Water Microfilter is one of the highest rated units at Amazon, with a user rating of 4.8 (out of 5) stars. While it's pricier, it's also more robust and the element filters all microorganisms larger than 0.2 microns (0.0002mm), producing clear, drinkable water no matter where in the world you are. This unit is light, but no light weight; it's very rugged and is used in some military applications. If I were going to be in a very remote location with little chance of support or a quick way out, this is the unit I would take. Otherwise, for most traditional uses, like water for hiking trips in the U.S., I would stick with the cheaper Hiker PRO.

Another top performer and widely used purifier is the MSR MiniWorks EX Microfilter. Also highly rated by Amazon users with a 4.5 (out of 5) star rating based on 60 customer reviews, the reason I think this unit plays second fiddle to the Hiker PRO is because it weighs in at a chubby 1 pound, while the Hiker PRO comes in at about 10 ounces. If you're a Backpacker you know what that means. However, for purifying camp water at non-hike in camps it would be a reliable unit, for sure. The filtration system is rated to 0.2 microns. And it's not to say that plenty of backpackers don't take this unit, they do, but for nearly equal performance and price there's no reason to lug around an additional 6 ounces when they both have 1 liter per minute output and remove nearly all of the harmful critters I'm worried about. One big plus for this unit is that its cartridge is rated to treat 2,000 liters compared to the Hiker PRO's 750 liters.

If you're going to need a larger supply of water, say for a true base camp or a larger hiking party, then the Katadyn Base Camp Water Filter is a great choice. It uses the same filter cartridge as the Hiker PRO and can produce 2 1/2 gallons of safe water in 15 minutes. If you take the Hiker Pro and this unit (minus the filter cartridge) you can simply share one cartridge for both units and save some weight. It's also really easy to use. Simply fill the reservoir with source water, hang the unit on a tree limb and let gravity do the work for you. As a gravity fed unit these are great for freeing you up to do other camp chores or simply enjoying your time; no more pumping.

Important Note: A large concern with purifiers (all of them) is that they cannot capture (remove) smaller viruses because the extremely small size of viruses allows them to easily slip through the pores of most filters. Even the purifiers with Iodine or other additives cannot cannot kill many of the viruses found in water. Some of these viruses are rather nasty (think Hepatitis A, rotavirus and Norwalk virus). In North America this isn't a huge concern, but when traveling elsewhere it would be good to include a SteriPen in your kit since UV light safely disables the viruses; in questionable areas I would filter the water then treat it a second time with the SteriPen.

SteriPen Ultra Shown Here
SteriPen Ultra Shown Here

How To Purify Water With UV Treatment

SteriPen Leads The Pack

As I mentioned earlier, the SteriPen Adventurer OPTI has been one of our backup units for some time now. It's fairly rugged when packed; the lid protects the light source pretty good and when packed snugly into the sheath there's little risk of the lid coming off. Best of all, this unit is really trouble free and can produce drinking water in less than a minute, and it kills virtually everything.

We've never had a failure with our unit, nor met anyone who complained of a failure with theirs, but it's worth noting that from the Amazon reviews some people have complained of a faulty Adventurer unit. Because of that, and since the Adventurer OPTI is an older model, I am including the link to the newest (brand new) SteriPen product, the Freedom Water Purifier. If I were buying a unit today (I may pick up one anyway) I would go with the SteriPen Freedom, for sure, because it meets the same standards but I'm sure it was designed to alleviate some of the complaints earlier models received, so should be even more reliable. Plus, the Freedom is rechargeable and somewhat smaller than the Adventurer.

The SteriPen Freedom was listed in the Mens Journal "Gear of the Year 2011" review.

SteriPEN Freedom Water Purifier - Treat Water For Hiking

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Most people take a water purifier (like the Hiker PRO) as their primary, but should have a 2nd and 3rd backup plan. What is your #2 plan to treat water for hiking or camp?

What do you pack for backup water treatment?

See results

Getting Water From the Animas

I would love to hear your comments about this article, or about camp water and what you do (or have done) to treat your water.

    0 of 8192 characters used
    Post Comment
    • SayGuddaycom profile image


      9 years ago

      I live on a boat so this is a topic that is on my mind very often. Great information.

    • Gayle Dowell profile image

      Gayle Dowell 

      9 years ago from Kansas

      I'm enjoying all of your outdoor survival and hiking lenses. I'm wanting to plan a women's hiking retreat this summer. Your lenses would be good to have the ladies read before going out. Thanks.

    • NatureLuver profile image


      9 years ago

      Great information.

    • SciTechEditorDave profile image

      David Gardner 

      9 years ago from San Francisco Bay Area, California

      Nice lens. Everything you'd want to know about H2O ... good stuff. Congratulations on a Squidoo masterpiece!


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