Water Purification Tablets: The Basics You Should Know

Purification of drinking water from a stream

Whether you’re heading out into the hills for a long backpacking trip or you’re travelling overseas to a place where the water is a little iffy, chances are good that you’ll want to have some method for making water potable.

Water is critical to human life as we know it, but in many parts of the world, it can also harbour all sorts of pathogens that can be dangerous to our health.

Thus, we need to find a way to treat our water to reduce the likelihood of contracting a nasty illness.

Especially for outdoorsy people and world travellers who adventure in places without modern sanitation systems and water treatment plants, there’s a high likelihood of contracting a waterborne illness.

Luckily, there are a number of different water filters and treatments that can make water potable regardless of where we are in the world.


​The Dangers of Untreated Water

Iodine vs Chlorine Water Purification Tablets

Even if your water is crystal clear, it may not be okay to drink. Even the most beautiful flowing water can harbour waterborne diseases, especially if you’re in a remote place in a developing country. The most common waterborne diseases, bacteria, viruses, and cysts include:

As you can see from this list, you definitely want to steer clear of untreated water. 

Although some of these diseases and illnesses will knock you out for just a week or less, others can easily turn deadly if left untreated. Unfortunately, millions of people around the world succumb to these diseases each year because they lack reliable access to clean water.

While your likelihood for contracting one of these illnesses is highest in the developing countries of South and Latin America, Africa, the Middle East, and Asia, outbreaks of some of these diseases have been known to occur in Australia, North America, and Europe, too. Thus, when backpacking or travelling, it’s better to take some extra precautions and treat your water.


​Types of Water Purification Tablets

Hiking and camping safe drinking water

​Water purification tablets are one of the many ways in which we can treat our water to kill off many of the common waterborne diseases, bacteria, viruses, and cysts. Essentially, water purification tablets are small pill-sized lumps of water treatment chemicals that can be used to kill off the microorganisms that cause waterborne diseases.

To use water purification tablets, one need only drop a tablet into the manufacturer's specified quantity of water (usually 1 litre) and wait for the specified length of time. At this point, one can presume that the chemicals in the water treatment have killed off these microorganisms and that the water is suitable for drinking. We always recommend following the manufacturer's specific instructions, but this is the basic idea for all water purification tablets.

Although they're pretty simple, as technology goes, there are quite a few different water purification tablets available on the market today, each with their own advantages and disadvantages. Here are a few different ones you should know about:

1. Iodine Tablets

Common brands: Potable Aqua, Polar Pure (liquid/crystal form)

Iodine is a chemical (a halogen, specifically) that is actually required in small amounts within the body for proper thyroid function. As a water purification method, it is very effective in killing giardia, which is the main cause for concern in backcountry water sources in North America but cannot kill cryptosporidium.

Iodine is a relatively cheap water purification method and can be found all over the world, which is why it is fairly popular among backcountry enthusiasts. However, it does create a very distinct flavour in your water, which some people really don't like. Plus, people with standard thyroid function can only take iodine for up to 6 weeks at a time and it's not recommended for people with thyroid complications, people with iodine sensitivity, and for anyone who is pregnant.

Pros
  • Affordable
  • Found all over the world
  • Effective against Giardia                        
cons
  • Weird taste
  • Maximum 6 weeks of use at a time
  • Ineffective against Cryptosporidium     

2. Chlorine-Based Tablets

Common Brands: Aquatabs (Sodium Dichloroisocyanurate)

Chlorine is the most commonly used chemical for purifying water. They are quick in the time it takes them to purify water, but, water treated in this method will inevitably become contaminated again if stored for a prolonged period of time.

Chlorine tablets, like iodine, are effective in killing giardia, but cannot eradicate cryptosporidium. Plus, it leaves behind a distinct chlorine flavour, which can only be eliminated by letting the water sit unprotected so the chlorine can evaporate. 

Pros
  • Easily found around the world
  • Can be used by people with iodine sensitivity
  • Effective against Giardia
cons
  • Stored water treated this way will become contaminated again
  • Bad taste
  • Ineffective against Cryptosporidium

3. Chlorine Dioxide Tablets

Common Brands: Potable Aqua, Katadyn Micropur, Aquamira (liquid solution)

Although it sounds similar to a chlorine-based tablet, chlorine dioxide-based tablets are wholly different. Chlorine dioxide tablets specifically operate using oxidation, which infiltrates a microorganism's cell walls and destroys the microorganism. Plus, unlike iodine and chlorine, chlorine dioxide is generally effective against viruses, bacteria, cysts and even the troublesome cryptosporidium.

Chlorine dioxide is a great tablet to use because it leaves behind significantly less aftertaste than some of the alternative options. That being said, it usually takes a bit longer to purify with chlorine dioxide than with other methods and it tends to be a bit more expensive.

Chlorine dioxide is also available in a liquid solution form, under the brand name, Aquamira, which is specifically designed for use in backcountry and international travelling situations.

Pros
  • Effective against most microorganisms
  • Can be used by people with iodine sensitivity
  • Minimal aftertaste
    Can be stored for a long time
cons
  • Longer treatment time
  • More expensive                                        

​Alternative Water Filters and Treatments

Steripen Australia

While water purification tablets are a great method for treating water, they’re not for everyone. They tend to be more expensive in the long run than other options and, since you can only carry a finite amount of purification tablets at one time, it’s possible to run out on a long trip. Thus, it’s always a good idea to consider other water treatment options before you settle on your method of choice.

Besides water purification tablets, the most popular methods of treating water are filters, UV, and boiling. Let’s look at them here:

1. Water Filters

Water filters are exactly what they sound like - they’re devices  that physically separate dangerous pathogens from our water. There are a few different kinds of water filters out there, but the most common are pump and gravity-powered. A popular option is the Katadyn Vario Ceramic Filter.

Pump filters require the user to physically pump the water through a ceramic filter. These can filter water fairly quickly, especially if you’re a solo traveller. Gravity filters, on the other hand, use the power of gravity to push large amounts of water through the filter to remove the pathogens.

Filters are great because they can filter out bacteria, dirt, and other debris, but unfortunately, the vast majority of filters on the market do not have pores small enough to block out viruses.

They’re also bulkier and heavier than many other water treatment options, so they’re not great for people travelling light and fast.

But, if you can’t use chemical treatments and want something that also cleans out the debris from your water, filters are a great choice.

Another popular option is the LifeStraw, as seen in the video below:

2. UV Radiation

UV radiation is useful in treating water because it affects harmful pathogens on a cellular level, which prevents them from reproducing and making us sick. It leaves behind no added taste and is effective on pretty much any pathogen you might find in your water.

This type of water treatment generally takes the form of a small battery-powered “wand” of UV light that you swirl around inside a bottle of dirty water. After stirring the wand in the water for a handful of seconds, the water is properly treated and can be considered okay to drink.

These devices are often sold under the brand name “Steripen” and are great for people who want to be sure that their water is free from harmful pathogens.

But, like anything battery-powered, they can fail, so it’s important to always have a reserve method for treating water.

​3. Boiling

Boiling water is the original method of treating it as it requires only a stove and fuel, which most backpackers already carry with them. Bringing water to a rolling boil is a great way to kill off pretty much anything that’s living in the water without affecting the taste or adding any chemicals.

The main downside to boiling water is that it takes time (though an efficient stove helps here) and fuel, which may be in short supply. But, boiling can rid your water of harmful pathogens, so it’s a great back-up water treatment option, even if it’s not your go-to choice.

About THE AUTHOR:

Gaby Pilson


A professional mountain guide and experienced outdoor educator, Gaby enjoys travelling and exploring the world’s most remote locales.


As a writer and editor, Gaby has written for a variety of climbing and travel blogs, news sites, and climbing magazines.


She is currently finishing a master’s degree in outdoor education but in her free time, Gaby loves a strong cup of coffee and searching for the next great adventure.

Categories Hiking