Water Purification for Travel: Best Methods For A Trouble-Free Trip

“Don’t drink the water” is a classic warning to travelers. But how much do you really know about purifying drinking water while traveling?

If the locals drink the water, is it safe for you to risk it? Is getting it wrong “just” a matter of spending a few days crouched in a pit toilet, or could you potentially catch something deadly? What’s the difference between a filter and a purifier? So many questions!

Those of us living in countries like the United States, where tap water standards are regulated, are extremely fortunate. Hundreds of millions of people around the world lack access to safe drinking water, which is a leading cause of death especially in children.

As travelers we have the privilege of avoiding most of these issues with a little preparation and knowledge, and most importantly a good travel water purifier. While I’m all for exchange of culture and perspectives when I travel, exchange of parasites and harmful bacteria is something I try to avoid.

In this guide I’ll lay out everything you need to know about purifying water during travel. After visiting dozens of countries across the full spectrum of development, including many where locals don’t have access to safe drinking water, I’ve thought a lot about this topic and researched all the options. Let’s get into it.

Purifiers Versus Filters

You might hear the terms “water filter” and “water purifier” and assume they’re interchangeable, but there’s actually a critically important difference: virus protection.

Water filters remove the bad stuff by catching it in pores that are too small for it to fit through. This works great for parasites and most bacteria, which are relatively large (microscopically speaking), but not for the tiny little viruses. It’s also nice for drinking water from natural sources which might have dirt or other larger particulates in it.

Filters don’t protect against viruses though — for this you need purification. Purifiers use an additional method, such as chemical or UV treatment, to kill viruses that would flow right through a filter and into your water bottle.

For travel in many “developing” countries where the sanitation infrastructure isn’t able to keep human viruses out of the water supply, you want to purify, not just filter, your drinking water.

A word of caution: I’m noticing lately that some products on Amazon use “water purification” or “purifier” in their titles when they are actually only filters. Presumably this is to optimize for searches from people who think purifying and filtering are the same. This one, for example, uses the word purification in the title but appears to be a filter. Read carefully!

Types of Waterborne Illnesses

To understand the pros and cons of the travel water purification options below, you’ll need to know a bit about the nasty little buggers we’re dealing with. There are three main categories of waterborne pathogens:

Bacteria

Bacteria, especially E. Coli, are the most common cause of water-related illnesses in travelers. Traveler’s diarrhea, Montezuma’s Revenge, Delhi Belly… Been there, done that, let’s not do it again!

Other examples of bacterial infections caused by contaminated drinking water include typhoid, cholera, salmonella, and campylobacters.

Bacteria are probably the easiest category for travelers to deal with. Their relatively large size means that filters remove bacteria easily, and chemical treatments like iodine and chlorine wipe them out reliably.

Parasites / Cysts / Protozoa

These nasty little critters can be as small as one cell. Common waterborne parasites include Giardia and Cryptosporidium. They are relatively large (microscopically speaking) so filters can easily remove most of them, and chemical treatments are effective against many of them with the exception of Cryptosporidium. Its hard shell resists chlorine and iodine and takes several hours to break down even with chlorine dioxide treatment.

Viruses

These are the tricky ones, and the biggest difference between water filtration for backcountry travel in countries with well-developed sanitation infrastructure (think hiking in the Rocky Mountains) versus travel in developing parts of the world.

Viruses are too small (0.02 – 0.3 microns) to be caught by water filters alone, so an additional purification method – like chemical or UV treatment – is needed in order to inactivate them. Some are simple stomach bugs while other are quite nasty diseases like Hepatitis A, Hepatitis E, and even Polio in a few parts of the world.

Down below I’ll talk more about how to make sure your water purification method protects against viruses.

Purification Versus Bottled Water

Travelers have long been advised to drink bottled water in countries where the tap water isn’t reliably safe. However, with increasing focus on environmental concerns (where is all that plastic going?) plus plenty of affordable and compact treatment options, there’s no reason to rely on bottled water any longer.

If saving the planet isn’t enough motivation for you, consider that treating your own water is convenient or even essential if:

• You plan to do any hiking or backcountry travel and need to drink from natural sources.
• You’ll be spending time in small villages where bottled water may not be readily available.
• You realize at midnight in your hotel that you’re out of bottled water and the nearest store is either closed or very far away.

Finally, if you travel often or to places with higher costs, treating your own water will save you money. Purifiers are relatively cheap, and the costs of bottled water can really add up.

Water Purification Methods for Travel

There are a number of ways to purify drinking water, some more convenient than others. Except where otherwise noted, all these methods are effective against all three forms of waterborne diseases: bacteria, parasites, and viruses.

Chlorine Dioxide

This simple chemical treatment is small, light, and easy to use: just squirt a few drops or drop a tablet into your water. It’s easy to scale up to treat larger quantities.

The downside: it takes time. You need to wait 30 minutes for it to work on most contaminants, and 4 hours for Cryptosporidium (though the wait time is the same for small and large quantities of water). It’s great for short trips, but you may not want to carry enough to use regularly on longer trips.

I find chlorine dioxide drops ideal for short and lightweight trips, and as a backup to another method on longer trips. I like to use them with two large bottles in rotation so I can drink from one while waiting for the other to be treated.

Pump Purifier

Pump purifiers use a combination of filter and chemical treatment to purify water. They’re very reliable and simple to use for treating large quantities, but the time spent pumping can be a pain if used frequently. They’re also bigger and heavier than most other methods.

Most purifier elements need to be periodically backflushed or cleaned, will eventually need to be replaced, and can be damaged by hard impacts or freezing temperatures.

Gravity, Squeeze, or Inline Purifier

Similar to pump purifiers, gravity purifiers use gravity to push water through the purification element instead of pumping. This makes them less labor-intensive, but gravity purifiers can be slow.

Cartridges used in gravity purifiers can also sometimes be set up as squeeze purifiers, where you push the water through by squeezing the dirty water container. If the flow rate is high enough they can also be used as inline purifiers, meaning you suck the water through the filter as you drink it.

Most purifier elements need to be periodically backflushed or cleaned, will eventually need to be replaced, and can be damaged by hard impacts or freezing temperatures.

Ultraviolet (UV) Treatment

UV treatment devices like the SteriPen treat water quickly and easily when you submerge the device, press a button, and wait a short amount of time.

However, as electronic devices they are vulnerable to issues like dead battery or bulb failure. They don’t work in cloudy water; not only will they fail to strain out particulates but they won’t effectively kill pathogens either. Treating large quantities of water can be awkward and you need to carefully consider your water container. But with the right system in place and relatively clear water water, they’re fast and easy.

Bottle Purifier

Bottle purifiers use various methods (UV, chemical, and/or filtration) to purify your water right in the bottle you drink from. This makes them very convenient for certain usage patterns (filling up a single bottle to go sightseeing for a day), but awkward for other cases (treating several liters at a time for camping or long days out).

Note that many bottle filtration products are only filters, not purifiers, and don’t protect against viruses. Be sure to check the fine print.

Boiling

If you have easy access to a stove and plenty of fuel, boiling is the simplest purification method. Bring the water to a rolling boil for 1 minute (3 minutes if above 6500 feet elevation) and it’s good to go.

The obvious drawback: the water will be very hot until given time to cool. Boiling doesn’t remove unharmful but gross gunk like silt and algae, which can be an issue when drinking from natural sources.

Unsuitable Water Treatment for Travel

Chlorine and Iodine – NOT usually suitable alone

Unlike chlorine dioxide, these classic water treatment methods don’t kill Cryptosporidium. Some people also don’t like the taste, or feel it’s unhealthy to use them regularly for long periods of time. Use chlorine dioxide instead.

Filters – NOT usually suitable alone

Any product marketed as a “filter” is most likely not a purifier, which means it won’t protect against viruses. When traveling in developing countries where viruses are a risk, a filter alone is not enough. Beware especially of bottle filters and straw filters, which are often marketed to travelers despite their lack of virus protection.

Note that some filters are marketed as “two stage” but even this doesn’t guarantee virus protection. The second stage may be a carbon filter that simply improves the taste, so read the fine print carefully.

You can, however, use a filter plus a chemical treatment for complete purification. The filter will take care of bacteria and parasites, and the chemical treatment will take care of viruses. I like the flexible and lightweight Sawyer Mini filter for this purpose, followed up by chlorine dioxide drops or tablets.

Where is the water unsafe to drink?

I hate generalizations in general 🙂 but I’m going to make one here: broadly speaking, the less “developed” a country is, the more carefully you should avoid drinking the tap water, or water from natural sources such as rivers, lakes and wells.

This is partly because places with less robust infrastructure aren’t able to create and maintain the large-scale systems needed to provide clean water at a country-wide scale. It also has to do with the more vicious microorganisms that thrive in equatorial climates, which (probably not coincidentally) tend to be correlated with lower development levels. And, in places without good sanitation infrastructure, diseases easily make their way into water supplies via human waste.

The best strategy for your trip is to search for details on the specific countries you’ll be visiting. To give you a rough idea, here’s how I personally think about the risk level of drinking water when I travel. This is my own system, not an official recommendation, so be sure to do your own research.

Level 1: Safe to Drink

In these countries you can expect to drink water directly from the tap with no adverse effects, even if you’re not from the area. The same doesn’t always apply to natural sources like rivers or lakes, which may be contaminated by from humans or animals and should be filtered (but usually not purified).

Examples: United States, Canada, Singapore, Hong Kong, Japan, South Korea, Israel, New Zealand, Australia, Finland, Ireland, Spain, many other European countries.

Level 2: Potentially Unpleasant to Drink

This is that murky middle category where the water is unlikely to seriously harm you, but it might ruin your trip. The locals might drink it, but the unfamiliar microorganisms can leave visitors chained to the toilet for a few days with a bad case of traveler’s diarrhea. Water quality might be unevenly distributed in these countries; it might be considered safe in the major cities but not in rural villages.

A few hardy travelers, especially those staying for months or more, might decide to drink tap water if the locals do. The hope is that a bout of illness is worthwhile if it leads to resistance and the convenience of drinking untreated water during a longer trip. Visitors on short trips, however, will probably want to drink treated or bottled water to avoid an unpleasant disruption to their itinerary.

People who are at higher risk for complications from illness – young, old, pregnant, immune-compromised – should still be very cautious about water purification in these countries.

In these types of countries I will usually drink treated or bottled water only, but brush my teeth with tap water. I may drink tap water in cities where it’s widely agreed to be safe.

Examples: Chile, Argentina, Bulgaria, Albania, Hungary, many others

Level 3: Dangerous to Drink

In these countries the local water sources can carry some seriously nasty, potentially deadly bugs: Hepatitis A, Typhoid, Polio, Guinea Worm Disease… These risks go above and beyond a bad case of traveler’s diarrhea.

Visitors to these countries should absolutely not drink the local water without purifying it (not just filtering it). Some locals might actually drink it, but only because they don’t have the means or knowledge to do otherwise.

My personal rule of thumb is that I even brush my teeth with bottled or treated water in these countries. I also try to keep my mouth closed while showering or washing my face.

Examples: Uganda, Ethiopia, Ghana, Nigeria, much of the rest of Africa, Nepal, India, Cambodia, many others

What about…?

Brushing my teeth?

As mentioned above, I’m more relaxed about teeth brushing. For countries I consider to be level 1 or 2 based on my research, I’ll brush my teeth with tap water, being careful not to swallow any in level 2 cases.

In level 3 countries where dangerous viruses are a serious concern, I won’t risk it. In these places I only brush with treated or bottled water, and try not to get water in my mouth when showering or washing.

Water in restaurants?

This depends on the restaurant. In touristy places it’s usually assumed restaurants will serve bottled water. In more locals’ areas you may want to ask. In high risk areas you might want to not risk it at all, choosing to bring or purify your own water.

Ice in drinks?

This also depends. In much of Southeast Asia, for example, I found that ice was made from bottled water. In West Africa I was not always so sure. In touristy areas it’s highly likely to be safe, but you can always ask.

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