Wait! We heard that you are trying to buy a water purifying tablet for your next hike. Before buying the water purifying tablet, it is always better to do some research. Here, read this article to know whether they are safe or not. So is it safe to add up the water purification tablet in your climbing gear?
How safe are water purifying tablets? It is most common for water purifying tablets to contain iodine, chlorine, or chlorine dioxide. Based on the average water consumption of an average adult, these tablets are relatively safe for people without underlying medical conditions.
It may be best to avoid water purifying tablets if you are pregnant or have a medical condition such as thyroid disease or allergies.

However it is also true that purifying tablets may not be the most effective method of purifying water, as they are not fully effective in killing viruses.
How Do They Work?
Chlorine, chlorine dioxide, or iodine are typically the active ingredients in water purification tablets. Tablets for water purification usually contain a variety of chemicals that dissolve in water if they are allowed to dissolved. Upon dissolving, these chemicals kill bacteria, viruses, and parasites. Chemicals kill these microorganisms by damaging their cell membranes, allowing chemicals to enter and deactivate them.
How Safe Are These Chemicals?
Chlorine:

Don’t worry, this isn’t the same type of chlorine used in swimming pools. Water disinfectants such as chlorine are widely used in municipal supply systems, so the majority of tap water that people consider safe to drink has been treated with chlorine.
Chlorine Dioxide:

Compared to chlorine, chlorine dioxide is an improved version. If you wish, you can call this chlorine 2.0. Compared to chlorine, chlorine dioxide can disinfect a larger volume of water for the same amount of chlorine. Also, it can work over a wider pH range.
Iodine:
A nutrient that is necessary to your body is iodine (which is why iodized salt exists). The problem with too much iodine is that it oxidizes proteins. Water purifying tablets do not contain high levels of iodine.
The typical concentration used to purify drinking water is about 3 mg/liter. In general, CDC recommends consuming at least 2-3g of iodine per day to be lethal. Hence, you’ll have to consume 1000 liters of water (264 gallons). Furthermore, because your body is capable of removing iodine naturally, it is near impossible to reach anywhere near the lethal dose.

Iodine, however, may present health risks for:
- Pregnant women: excessive iodine can affect thyroid health
- When someone has hypothyroidism or hyperthyroidism, the thyroid may produce too little or too much hormones depending on the level of iodine in their system
- People with an allergy to iodine
Nausea and headaches are common side effects.
In spite of this, it is noteworthy that EU law prohibits the use of iodine to purify water. Despite its use in other products (such as salt), iodine is not packaged for water purification.
Effectiveness of Water Purifying Tablets in Preventing Bacteria and Viruses
In the wilderness, human and animal waste is the most common source of bacteria, viruses and protozoa in water. They can lead to disease, illness, or even death. During wilderness activities, cryptosporidium and Giardia are commonly encountered harmful microbes.
- The bacteria (such as Campylobacter, Salmonella, Shigella, Escherichia coli)
- Water that is contaminated with bacteria can cause gastrointestinal health effects like diarrhea, vomiting, and cramps
- In drinking water, bacteria are usually found in feces of humans and animals
- Viruses (such as Enterovirus, Hepatitis A, Norovirus, Rotavirus)
- Water that is contaminated with viruses can cause gastrointestinal health effects like diarrhea, vomiting, and cramps
- In drinking water, viruses are usually found in the feces of humans and animals
- Cryptosporidium
- Drinking contaminated water can lead to gastrointestinal illness including diarrhea, vomiting, and cramps
- Drinking water contains Cryptosporidium that come from human and animal waste
- Giardia
- Drinking contaminated water can lead to gastrointestinal illness including diarrhea, vomiting, and cramps
- Drinking water contains Giardia that come from human and animal waste

Chlorine | Chlorine Dioxide | Iodine | |
Bacteria | Kills bacteria very effectively | Kills bacteria very effectively | Kills bacteria very effectively |
Viruses | Kills viruses very effectively | Kills viruses very effectively | Kills viruses very effectively |
Cryptosporidium | Has no effect on Cryptosporidium | Has low to moderate effect on Cryptosporidium | Has no effect on Cryptosporidium |
Giardia | Has low to moderate effect on Giardia | Kills Giardia very effectively | Has low to moderate effect on Giardia |
Note that water purification tablets cannot remove sediments or toxins. Filter the water before adding the tablets to remove any sediments.
How Do I Use The Water Purifying Tablets?
Water purifying tablets are typically used as follows:
- With a paper filter or a thin cloth, remove any sediment from the water.
- Pour chlorine tablet(s) into the water (make sure you use the correct number of tablets for the amount of water you are purifying).
- If you’re using iodine tablets, you need to wait about 30 minutes before getting rid of all contamination (check the packaging for the waiting time, it might be longer in some temperatures and conditions).
- If you wish, you can flavor or neutralize the water to remove the taste of chlorine or iodine. It is also possible to remove the chlorine taste by allowing the treated water to sit uncovered so the chlorine can evaporate.
If they are not used correctly, all water purification tablets will not provide complete purification. Use the product according to the instructions on the packaging.
Is Water Purification Tablets Harmful If Accidentally Ingested?
Do not consume the tablets unless they have been dissolved in water. Any tablets eaten or swallowed should be immediately reported to a healthcare professional. See if there are any instructions on the package regarding accidental ingestion.
Which Are Some Well-known Brands Of Water Purifying Tablets?

Here are some of the most common water purifying tablets used by climbers and hikers:
- Chlorine tablets (Aquatabs)
- (Chlorine dioxide tablets) Katadyn
- Tablets of chlorine dioxide and iodine in water (Potable Aqua)
What is the price of water purification tablets?
It is usually the most affordable method of disinfecting water to use water purification tablets. Some examples of their costs:
- Aquatabs (chlorine tablets) cost about USD 8 for 100 tablets
- Katadyn (chlorine dioxide tablets) costs approximately USD 12 per tablet
- Aqua potable (chlorine dioxide tablets): about USD 12 for each 20 tablets
- The price of 50 tablet of potable aqua (iodine) is around USD 10 (including taste neutralizing tablets).
Can water purifying tablets last for a long time?
Water purifying tablets can last for years if stored properly.
Sunlight, high temperatures, and humidity may speed up the degradation process, which is why your tablets are usually packaged in foil or dark bottles and therefore they should be stored in a cool, dark place.
The expiration date may affect the effectiveness of the water purifying tablets. Tablets should not be used beyond their expiration date since their effectiveness might be reduced. There is no point in taking a chance here.
What Is The Best Place To Collect Drinking Water?
Water purifying tablets are not the only way to purify water. Don’t collect water from nearby areas as it can pose significant health risks:
- Waste factories that produce chemicals, metals, or other manmade waste
- Farms that raise poultry
- Pools of stagnant water

In general, wild water collected from natural sources can be safely consumed without further treatment or sanitation. A survey of 69 backcountry sites in the US for example showed that the concentration of Giardia cysts found in every site were too low to cause illness.
Sometimes this video might also help!
Frequently Asked Questions (FAQs):
Are iodine water purification tablets safe?
In powder, liquid, and tablet form, portable water purification chemicals contain iodine or chlorine. Adding them can kill harmful microorganisms in untreated water and make the water safe to drink. These tablets are generally safe, but cannot be easily distinguished from medications or candy.
Are chlorine water purification tablets safe?
In powder, liquid, and tablet form, portable water purification chemicals contain iodine, chlorine dioxide, or chlorine. Adding them can kill harmful microorganisms in untreated water and make the water safe to drink. These tablets are generally safe, but cannot be easily distinguished from medications or candy.
Can you purify water with chlorine or iodine?
Bacteria and viruses are effectively killed by chlorine and iodine. The disinfectants will not be able to kill parasites such as Cryptosporidium, however. Especially in an emergency, it is difficult to know whether parasites are present. The best way to make water safe if you cannot boil it is by treating it with more than one method.