Is Water From a Waterfall Safe to Drink?

There is a piece of prepper lore that tells us water from a natural source that is fast-moving, bubbling, or rapid is safe to drink from. Conversely it informs us that we should never drink from slow moving, nearly still or standing water.

If you consider this advice it would seem that sourcing water from a waterfall would check all of those desirable boxes, being both frothy and rapidly moving. It certainly looks refreshing.

the Gullfoss waterfall in Iceland
the Gullfoss waterfall in Iceland

But is water from a waterfall safe to drink?

No, water from a waterfall is not inherently safer or less safe than water taken from any other natural source. The quality of the water is dependent upon contaminants that have entered it from upstream.

Dirty water that goes over a waterfall is still dirty water and can still make you very sick or worse you if you drink it without treatment.

Sadly, waterfalls do not work as any sort of natural purification method, and water heading for a waterfall does not necessarily originate from any pure or inherently safe source.

There is more to consider on this matter; we will discuss it below.

Waterfall Water Does Not Equal Clean Water

Although I’m not entirely sure where it originated from, the old timers’ wisdom that informs us whitewater, rapids and other rushing forms of fast-moving water are somehow safer sources of drinking water has persisted over the many decades right up to today.

The surest sign of a greenhorn prepper or outdoorsman is them believing in this falsehood

Regardless of how it got started or why, you can at least understand the reason behind it: water that is bubbling and frothy appears clearer and cleaner than it would when it is moving slowly or standing still. It certainly looks more refreshing if you ask me!

Unfortunately, there is no mechanical or chemical process at play that purifies the water moving through rapids or down a babbling brook, or over the long drop of a waterfall. Whatever contaminants are in the water remain even as it sloshes and froths.

Whether you take it from a still source or a fast-moving one, you are still going to have to treat and purify your water, unless you want to roll the dice on contracting some kind of nasty ailment.

Contamination Carries

The crux of the problem when comes to water contamination, including the contamination of water heading over a waterfall, is that anything in the water upstream from where you source it could potentially be carried downstream…

For instance, you might be drawing water from what appears to be a crystal clear and utterly pristine part of the stream in the deep, remote reaches of Alaska.

“It is probably fed by glacial runoff”, you think to yourself, “and has been locked in stasis completely untouched by the ravages of mankind’s pollution for all these many centuries until this very day!”

“This is probably the purest water you are ever going to taste”, you think out loud, as it trickles into your canteen, burbling and utterly cold.

Unfortunately for you if you had walked just another 125 yards upstream from where you are standing at that very moment, you would find the gargantuan corpse of a Yukon moose that is already badly decomposing, no doubt infusing the entirety of the water with all manner of bacteria and by-products of necrosis.

Unwittingly you take a long swallow of cold, clear but totally moose-y water…

This is super gross, because of course it is, but more importantly, you are probably now on the fast track to catching some hideous disease, or at the very least getting very sick to your stomach, neither of which is a good thing in the backcountry, and either of which could spell certain death if you are already in the middle of a survivor situation.

Waterfalls Are Not Pristine Sources

Keep in mind that the water being sourced at the waterfall is not necessarily any purer than the water mentioned in the previous (and hopefully only hypothetical) example.

It isn’t burbling up to ground level directly from the spring. It is not pure glacial runoff taken immediately from the source.

Most water has to go a very long way before it reaches a waterfall, and that means it will be exposed to all kinds of potential contaminants, natural and man-made.

As time goes on, the once remote and nominally pure natural sources of water have suffered from increasing contact and contamination from man-made forces.

Industrial accidents, oil drilling, fracking, litter, rerouting of rivers, disturbing of animal migratory paths, and innumerable other factors all lead to an increase in contamination for most of our natural water sources. This results in first, second and third order effects.

But even without the interference of mankind, or just a minimally invasive presence from man, water found out in the world is simply often filthy.

Animals drink from it. They walk in it. They bathe in it, and poop and pee in it. And as mentioned they even die in it. Fish lay their eggs in it, and die in droves in it.

Put a sample of water taken from any natural source on a petri dish, fire up your microscope and strap in!

You are about to see a universe of microscopic life through the eyepiece, many of them disease-causing organisms or parasites, and tons of other debris and sediment besides.

Consider that the river or stream feeding your waterfall might make a journey of many a-mile before it reaches the falls themselves.

In that time I could pass countless farms and all their runoff, industrial sites, many thousands of animals making use of the water in one way or another, hundreds of animals that have died in it and untold amounts of litter.

This hideously filthy water is even now making its way to your canteen or water bottle.

The roaring, splashing water going over the edge of a waterfall is not somehow made miraculously clean by doing so. Thinking that it is a major mistake.

Common Waterborne Germs and Ailments

The following, short list is made up of common, and devastating, germs and diseases that might be waiting for you in that seemingly fresh and clear water your just drew from the waterfall.


Dysentery is an intestinal infection that causes inflammation and bleeding in the gastrointestinal tract.

Although dysentery can be caused by both bacteria (shigella bacillus) and amoebas, bacterial dysentery is more common and severe.

Symptoms of dysentery include bloody diarrhea, abdominal pain, and fever. If left untreated, dysentery can lead to dehydration and death.

Dysentery is most often spread through contaminated food or water, making proper sanitation essential for preventing the disease.

With proper treatment, however, most people with dysentery make a full recovery, but you probably won’t have that luxury in the wilderness.


Giardia is a microscopic parasite that lives in the intestines of animals and humans. Giardiasis, the infection caused by Giardia, is one of the most common waterborne illnesses in the world.

Symptoms of giardiasis include diarrhea, abdominal cramps, bloating, and flatulence.

Giardia is commonly spread through contaminated water, and can also be transmitted through contact with infected animals.

Giardiasis is usually not severe, and will resolve on its own, but it can be very unpleasant while it lasts. Major complication is additional dehydration due to diarrhea.

E. coli

Escherichia coli, better known as E. coli, is a type of bacteria that lives in the intestines of animals and humans. Although most strains of E. coli are harmless, some can cause serious illness.

Symptoms of E. coli infection include diarrhea, abdominal cramps, and fever. In severe cases, E. coli can lead to kidney failure and death.

E. coli is usually spread through food and especially water that has been contaminated with fecal waste, and can also be transmitted through contact with infected humans or animals.

E. Coli is highly vulnerable to common methods of disinfecting water, including, UV, chlorine and boiling. Make sure you treat your water so you don’t run afoul of this germ!


Salmonella is a type of bacteria that is a common cause of food poisoning. Salmonellosis, the infection caused by Salmonella, is characterized as a bad stomach flu with all that entails, including vomiting and severe diarrhea.

Once again, dehydration and electrolyte loss is a major threat without supportive care when in austere or remote environments.

Salmonella is stereotypically spread through contaminated food (especially poultry), but can also be transmitted readily through surface water as well.

Like many of the germs on this list, simple field treatment methods can exterminate this germ before it gets you.


Cholera is a usually waterborne disease caused by the bacterium Vibrio cholerae. Although virtually unknown in industrialized countries with good sanitation and sewage disposal practices, it nonetheless persists in many remote areas and developing countries.

Cholera is characterized by severe diarrhea and vomiting, which is easy enough to treat with care but may once again cause massive dehydration and easily result in death if left untreated.


Colloquially known as “crypto” and we aren’t talking about the currency.

A nasty little parasitic protozoa, this one causes the affected to pass large quantities of watery diarrhea and is often accompanied by a persistent cough and intense abdominal pain.

Notably some strains are resistant to chlorine and other forms of chemical sterilization, so make sure you filter or boil to deal with this bugger.

Waterfall-Sourced Water Must Be Treated

This is a long-winded way of saying that you must treat water sourced from a waterfall the same as you would water taken from any other natural source.

If you have a water filter, definitely employ it. If you use chlorine or other sterilization tablets, do so now. Filter it and then bring it to a roiling boil, triple treat it.

Whatever you do, do it. Just make sure you are treating it if you want to minimize the chances that you will contract something nasty from it.

How Can You Tell if Waterfall Water is Contaminated?

You can’t by sight, smell or taste. Crystal clear, delicious water may still contain harmful or deadly viruses, bacteria or other pathogens. Assume all water flowing over a waterfall is contaminated with various nasty things you don’t want to infect you.

The good news is that most of these waterborne germs can be killed by common methods of field water treatment.

Should You Test Waterfall Water?

You can, though chances are you won’t be packing reliable test equipment in your bugout bag or hiking pack. A better bet is to just assume that any water source you draw from needs treatment.

Are there Any Waterfalls that are Safe to Drink From?

None that you could say are 100% safe with certainty, either by type or source.

Theoretically there may be a small waterfall burbling over the edge fed directly from a remote mountain spring, somewhere, that is the cleanest water you might ever have, but you won’t know for sure.

Again, and I belabor the point: treat, treat, treat your water!

1 thought on “Is Water From a Waterfall Safe to Drink?”

  1. any water unless it comes from the mains should be viewed as suspicious and treated before use.
    even more so is a survival or emergency situation where medical treatment is not available.

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