Contaminated water is your biggest enemy when traveling. You can’t see with your eyes if the water in a glass is safe to drink, whether it contains billions of microscopic bugs that will make you sick, or whether it’s pristine and perfectly safe.
It’s not just unsafe food. Waterborne illnesses are one of the most common health problems of travelers. Because you use water to drink, clean, or wash so often, it’s easy to make a mistake and have a couple of days ruined by stomach problems.
In this article, you’ll find out where water is safe to drink, what to avoid, and how to make water from unreliable sources safe using different purification methods.
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Understanding the Risks of Tap Water Abroad
Tap water quality is one of the leading indicators of a country’s development. It’s closely tied to sewage management, sanitation, and freshwater availability.
Safe drinking water for everyone is one of the WHO’s main goals, and we’re still far from achieving this. According to UNICEF,
„In Africa, 418 million people still lack even a basic level of drinking water service, and 779 million lack basic sanitation services (including 208 million who still practice open defecation).“
The main risk of drinking tap water in countries with poor water treatment is contracting bacterial, viral, or even parasitic infections.
The most common bacteria present in contaminated water are E. coli and Salmonella. Together with norovirus, which is mostly contracted from human to human, they’re usually responsible for travelers‘ diarrhea.
Other risks include high levels of lead, arsenic, common drugs, antibiotics or hormones from contraception pills, and the latest problem, microplastic. These can also be found in developed countries and have long-term health impacts.
When traveling, start with a simple Google search. „Can I drink tap water …“ (in Mexico, Japan, Uganda, etc.) You’ll find the answer quickly.
Sometimes, locals will tell you the water is potable, and they drink it. I wouldn’t take their advice as their immune system is used to the bacteria. After having stomach problems a few times, you might be able to drink it as well, but who wants that?
Even countries with safe tap water can have problems in some locations, like coastal areas and islands where water is scarce. Yes, you got it. These areas are usually the touristic ones. Don’t drink tap water if it smells bad or isn’t colorless, especially after heavy rainfall.
Remember to close your mouth while showering, brush your teeth with drinking water, and wash your fruits and vegetables in drinking water.
Ice Cubes as a Trojan Horse for Tap Water in Your Drink
You never know if drinking water was used to make ice in your drink. Order drinks without ice when in areas with untreated or possibly contaminated water.
You can always ask the staff, but use your instinct as well. The more sketchy the place and the seller, the more likely they will lie to sell the product.
Moreover, very cold drinks in hot climates can have a laxative effect without being contaminated. Skip ice if you can, or make sure the ice is made from drinking water. And no, the alcohol in the drink won’t disinfect the water unless the concentration is over 60%. Good luck drinking that.
Is Swimming in Freshwater Safe?
Swimming in lakes and rivers has many risks. If we focus on the microbes that may be swallowed and cause diarrhea, we can say this: Colder water is safer than warm. Water that’s flowing is safer than still water. Jumping in the water or doing water sports increases the risk of swallowing the water.
The CDC recommendation is: „Do not swim near storm drains; in water that could be contaminated with human or animal feces, sewage, or wastewater runoff; in lakes or rivers after heavy rainfall; in water that smells bad, looks discolored, or has algal mats, foam, or scum on the surface.“
Bottled Water Is The Easiest Option
Bottled water is the safest option while traveling. Still, there are some rules you should follow.
Buy drinks from reputable stores made by reputable brands. Typically, two or three brands are sold in every store. Just check that the cap hasn’t been broken. Some bottles have a plastic seal over the cap.
Although I’ve never seen one, counterfeit bottles could be refilled with tap water and sealed with glue. If the cap makes a nice cracking or popping sound, you’re good to go.
The greatest downside is the plastic waste from the bottles. Sadly, you need them most in countries that don’t recycle. You can reduce the waste and save money by buying the largest package available and refilling your bottle.
If your accommodation has a filtration system for making drinking water, refill it there. Or make your own drinking water anywhere!
Water Purification Methods
There are a couple of methods for water treatment. If you travel a bit, hike, or go camping, they might be cheap, convenient, and wasteless options. Each method has its pros and cons; pick one that suits you or your travel plans.
1. Boiling water – simple and effective
The easiest way to kill the microorganisms in water is to give them a little jacuzzi. After water boils for a minute (or three minutes in high altitudes), it should be safe to drink.
This is very practical if you feel like drinking tea or coffee, but waiting for the water to chill is not very convenient. You won’t use it much if you don’t have a kitchen at your accommodation or a portable gas stove.
Pros:
- easy to do
- not compromised by the particles or cloudiness of the water
- kills bacteria, viruses, and parasites
- doesn’t change taste
Cons:
- fuel needed
- long waiting time to cool down
- no residual protection
- doesn’t change taste (if bad)
Use case: Trekking in an area with snow that has to be melted before drinking, tea lovers
2. Ultraviolet radiation (UVR)
UV light kills bacteria, viruses, and protozoan cysts. To be successful, you will need the right type of UV light, the right dose, and the right exposure time.
Anything that blocks the radiation, such as water that has high turbidity or contains sediments, could make this method ineffective.
There are bottles with caps radiating UV light that can effectively treat tap water abroad. Using water from natural sources is not advised without previous filtration because of the sediments.
Another method using UVR is Solar Irradiation/disinfection, or SODIS. It uses transparent bottles exposed to sunlight for 6 hours or more. Under cloudy weather conditions, the process takes two consecutive days.
However, this is more of a survival method than something useful in everyday travel. The most popular UV purifiers are bottles from Larq.
Pros:
- small device with a battery, effective against all waterborne pathogens
- no harm to the body if using extra doses
- relatively cheap
- no taste change
Cons:
- requires clear water
- needs to be charged
- can’t know if the device delivers the right amount of UVR
- no residual protection
- no taste change
Use case: Treatment of tap water abroad.
3. Chemical disinfection
These are chlorine and iodine-containing compounds. They are produced as water purification pills/tablets, drops, or in granular form.
They effectively destroy bacteria and viruses. At the right concentration, they’re effective against Giardia cysts but not against Cryptosporidium. This parasite can be killed only by Chlorine Dioxide.
We have to note that iodine is active in the human body. It is taken up by the thyroid gland and should not be used for more than a few weeks.
Thyroid disease, pregnancy, or iodine allergy are conditions when iodine-disinfected water should not be drunk.
Chlorine and Iodine compounds, Sodium hypochlorite (found in bleach)
Pros:
- cheap, available
- small package of tablets or drops
- usable in small and large volumes
- residual protection
Cons:
- can worsen the taste and odor (can be removed by adding vitamin C)
- the possibility of overdose
- iodine can have adverse effects
- not effective against Cryptosporidium
- can stain clothing
Chlorine Dioxide
Pros:
- cheap, available
- small package of tablets or drops
- usable in small and large volumes
- effective against Cryptosporidium
Cons:
- sensitive to sunlight and air
- no residual protection
- takes several hours to work properly
Use case: Traveling in groups treating large volumes of water at once. Non-frequent outdoor travel. Backpacking as light as possible.
Iodine-based purification tablets on Amazon: https://amzn.to/4fJAl9a
Chlorine-based purification powder on Amazon: https://amzn.to/40H3cqa
4. Filtration
Hand pump, pressure, or sucking systems are available in all sizes and colors. The most important thing is the pore size of the filter.
For filtering parasites, bacteria, and viruses (in order from the largest to the smallest), we need a pore size of 0.01 µm (Ultrafiltres). As it gets smaller, it also gets harder to filter. (The suction will make you use the jaw muscles so much that you’ll get the Chad face).
Nanofiltres will remove chemicals and large molecules, and products using reverse osmosis will even desalinate the water. (You can drink from the ocean.) However, because of their size and price, they are used by military and marine travelers, not by regular travelers.
The best water filtration bottles for travel are from Grayl and Lifestraw.
Pros:
- simple to use
- fast
- diverse products available
- improves taste
- reliable
Cons:
- takes space and adds weight
- some filters don’t remove viruses
- expensive
- require maintenance
- can become clogged by particles
- no residual protection
Use case: Frequent travelers. Hikers using natural water sources. Traveling in countries with very poor sanitation.
Stay Hydrated and Healthy on Your Travels
I hope you have chosen your water purification method by now. If not, check out this great article by CNN about the best filtered water bottles.
Drinking enough safe water is crucial, especially in hot climates and on airplanes.
Stay safe and healthy by following our evidence-based blog posts and social media. Subscribe to our newsletter for exclusive information and travel health news from around the world.
Enjoy your travels!
Resources
https://wwwnc.cdc.gov/travel/yellowbook/2024/preparing/food-and-water-precautions
https://edition.cnn.com/cnn-underscored/reviews/best-filtered-water-bottle
https://www.qssupplies.co.uk/worlds-most-dangerous-drinking-water.html
https://bigthink.com/strange-maps/drink-tap-water-50-countries/
https://epi.yale.edu/measure/2024/H2O
https://www.cdc.gov/healthywater/drinking/travel/index.html
Centers for Disease Control and Prevention (CDC), and Jeffrey B. Nemhauser, CDC Yellow Book 2024: Health Information for International Travel (New York, 2023; online edn, Oxford Academic, 23 Mar. 2023), https://doi.org/10.1093/oso/9780197570944.001.0001
Disclaimer:
The information provided in this blog post is for general informational and educational purposes only and is not a substitute for professional medical advice. Always consult your physician or other qualified healthcare provider with any health problem. The use or reliance on any information provided in this blog post is solely at your own risk.
