Water Purification vs Water Filtration

For most folks in the developed world, getting a drink of safe, clean, palatable drinking water is as easy as turning on the tap.

Outside of the comfortable amenities of home, however, attaining potable water can get more complicated and require more effort.

Maybe you went backpacking with all the proper gear and simply didn't allot the correct amount of water for the trip. Or you're traveling in an undeveloped country and have been warned not to drink from the tap. Perhaps the SHTF and you're trapped in a city without a clean water source (or less apocalyptically, you're simply living in a town whose water source has been temporarily contaminated).

How would you procure clean drinking water in these circumstances?

The right methodology might be different for all these scenarios, as it depends on where you are, your budget, how long you need your filtering materials to last, etc.

The options for filtering and purifying water are in fact numerous, and unfortunately, some of the terminology related to them is also confusing, and not necessarily standardized (especially on the web).

So below I provide a crash course on water filtration and purification for camping, survival, and travel. I break down the consequences of drinking untreated water, the proper terminology to understand when researching and shopping filtration and purification methods, and the pros and cons of the methods themselves.

The Risk and Consequences of Drinking Contaminated Water

There are a number of bacteria and parasites that can be ingested and lead to illness through the drinking of untreated water.

How do these diseases get into water sources? In both the wild and in populated areas with poor sanitation practices, it's often carried by humans and animals (and their waste) who hunt, live, bathe, defecate, and even die or get their remains thrown in lakes and rivers.

In the wilderness of the U.S., a primary waterborne illness is called giardiasis. It's a protozoan parasite that can cause extreme cramping, and worst of all in any outdoors scenario, violent diarrhea.

Throughout the wilds of the world, other waterborne diseases include dysentery, cholera, and various other worms, viruses, and bacterial infections. The most common symptoms that arise from these illnesses are similar to giardiasis in that they're largely intestinal issues. When you're perhaps already dehydrated in a survival scenario or even just from backpacking for a few days straight, diarrhea will exacerbate the problem, and even put your life at risk.

Far better to treat any water you drink from the wild or from questionable sources rather than risk a debilitating illness. The only exception is if your life truly depends on getting hydrated. In that case, absolutely drink untreated water. As is often said in wilderness survival circles, doctors can treat giardiasis, but they can't treat dead.

Does All Water Need to Be Treated?

In the wild, rainwater you've collected in clean containers is generally safe, as is snow that you've melted. Water in the wilderness is also almost always safe if you've collected it via transpiration or a still (if the plant itself isn't poisonous, of course). If you collect the water by any other means, though — from a stream or lake (flowing water is better than stagnant, but still not foolproof), dew, etc. — it should be filtered and/or purified; you never know what might be lurking in the ground or upstream from your collection spot.

In urban areas, rainwater may not be safe to drink, as it traveled through polluted air. And if you're traveling in a developing country where the safety of the tap/well water is questionable, you'll want to stick to drinking bottled water (not always an option in rural areas), or consistently purify your water.

Water Purification vs Water Filtration

When it comes to finding and drinking water, the first thing you need to know is the difference between filtration and purification. They are not synonyms.

Water filtration is the elimination of debris, and some bacteria, by way of some type of cloth or mesh net — a sieve — through which the water flows.

Water purification is a chemical or UV process of rendering bacteria and other harmful agents inoperative. The chemicals (or heat) in these purification methods essentially deactivate the bad stuff, making it safe for consumption.

Sometimes water needs both of those processes; sometimes it only needs one. Knowing the difference, though, can truly save your life. If you're backpacking in Africa and think you only need a filter, you could end up with a deadly disease in your system. So let's get a little more into the differences between the two.

Water Filtration

Using a water filter, especially a commercially tested one (versus just the DIY backwoods variety), can indeed eliminate some bacteria. But not all. Filters can take care of protozoa and bacteria, but they can't get rid of any viruses present in the water — those are simply too small for the mesh to catch.

Generally, for backpacking and survival purposes, water in the U.S. and Canada is rated as safe for filtration-only methods and devices; this is especially true for mountainous areas. When folks get sick while backpacking or camping and blame it on the water, it's often found to actually be sanitation-related (not washing hands, not disposing of waste properly or far enough from campsite, etc.).

Filtering water also ensures the best flavor. Your H2O will taste natural and will be immediately drinkable, whereas some purification methods either alter the taste and/or take up to a few hours to make the water safe.

The bottom line is that filters work to rid the water of impurities — including dirt as well as microscopic bacteria — but aren't completely effective in making the water safe to drink. If it's all you have, you'll likely be okay, but know that negative consequences are still possible.

Water Purification

Water purification makes H2O safe to drink by deactivating all harmful pathogens, including viruses. Purification doesn't eliminate contaminants though. Dirty water that's been purified is still dirty water, and probably needs filtering (that should happen first, actually).

Purification happens primarily through boiling, chemical agents, or UV light. It's especially important when traveling outside first world countries, where viral infections are more common.

Let's now take a look at the various filtration/purification methods out there.