Is Glacier Meltwater Safe to Drink?

In this text you have my thoughts about drinking glacier meltwater, with some potential hazards mentioned, and with the ways of dealing with it if you have to drink glacier water. I myself never drink such a water before it is filtered.

If you think that drinking water from glacier lakes and streams, that look so clean, is safe, think twice. Glaciers collect lots of natural and artificial pollution from the air and from the surrounding area.

Such materials may be buried in the glaciers for hundreds or thousands of years before they are washed away when the glacier melts. So it is best to avoid drinking glacier water before filtering it, or it is even better to purify it.

Make sure you have a purifier with pores as small as 0.02 microns, and if possible also equipped with an activated carbon.

Is Glacier Meltwater Safe to Drink - top picture showing a Swiss glacier.
Glaciers in Swiss Alps, from one of my tours.

Natural pollutants in glaciers waters

Glaciers may look so inviting, clean, and fresh, and the water coming from them looks perfectly clean. You have seen the top picture above, this is from one of my tours in the Swiss Alps.

But have you ever seen a glacier late in the season when the fresh snow is melted? If not, then you would see something similar to the picture below:

A dirty glacier.
A dirty glacier.

So this glacier may look completely white in the beginning of summer. What makes the difference? With snow that accumulates every winter, there is lots of dust and other pollutant that are in the snow. In fact, snow crystals tend to form around such tiny particles in the air, and this all ends up in the snow.

Now, this happens every year, for thousands of years. As a result, the glacier becomes more and more dirty. New snow does not necessarily melt every season, so a part of it may remain, and this is how the glaciers grow, with all the stuff conserved in them.

You may think that the dirt in the picture above is mostly man-made, this may be so, but again, think about thousands of years. Pollution by humans is a more recent problem. So most of the dirty stuff there is natural.

Is it just dust or something more?

The dust trapped in the ice is not necessarily a health risk, but there may be many more things there. I have a separate full text with some news which you should have a look at.

Namely, they found 33 virus groups in only two ice core samples in the Guliya ice cap on the Tibetan Plateau. But wait for this; 28 of these groups have been previously unknown to scientists. They have been sitting there in the glacier for many millennia.

Carcasses of animals

Animals should be rare on glaciers, but they are in the areas below them, where they have plenty of water and grass. Sometimes they get killed by falling rocks, see the picture below from one of my tours, or they have an accident. Oh yes, alpine goats are great climbers but even they can make a wrong move.

Animals can also die because of a disease and they may end up in water flows, see the other picture below from my another climb.

Now, if you are somewhere below, and you see the water spring with its crystal clear water, and you are thirsty…But think about these pictures before you refill your bottle.

Man made pollution of glaciers

There is a research paper by R. Ambrosini et al. where they analyzed samples from the Forni Glacier in the Italian Alps, and concluded that the glacier area should contain 131–162 million microplastic items. This contamination gets there by winds and air streams and consequent wet and dry deposition.

Such stuff degrades and disintegrates due to photodegradation and other processes and it eventually end up in the water as micron and submicron particles, and you will drink it if you do not use filters. More is available in my separate text.

But there is more fascinating stuff related to glaciers and man-made pollution. Researches did analysis of the Monte Rosa glacier and found lead pollution that came from England from the period 1170-1220. It arrived there due to atmospheric circulation and winds. This all is related to the assassination of Thomas Becket, the Archbishop of Canterbury, all details are in my another text.

Think also about people peeing and defecating on the glacier in the past, bodies of dead soldiers from the WWI in the Italian Alps. It all remains there until the glacier is melted…

Do you remember the story about the Roopkund glacier lake in the Himalayas? There are more than 600 skeletons of human bodies in it, with flesh attached and well preserved. Think about such things before you refill your water bladder next time in a beautiful glacier lake.

There are mountain huts very high in the glacier areas. I could give you many examples from the Alps. They are visited by hundreds of people in busy days. They all need to go to the toilet or to an out-house, so think a bit, where all that stuff ends up?

See the photo below, this is a beautiful glacier lake under Monte Leone in Swiss Alps. It looks crystal clear but I would not drink water from it. The hut is directly above it.

A glacier lake near Monte Leone hut in Swiss Alps.
A glacier lake near Monte Leone hut in Swiss Alps.

What about per- and polyfluoroalkyl substances (PFAS)? These are man-made and very hazardous chemicals that are present globally in the atmosphere. They can be found in the rainwater and snow in the most remote locations on the planet.

Unfortunately, there is no easy way to remove them from the water, no matter if this is meltwater from the snow or in general. But we are exposed to them in our daily life in various ways, so having them extra in the meltwater is nothing new. However, water filters with activated carbon can remove most of them from the water.

How do you test if water is safe to drink in the wild?

This is an actual question that people ask so I feel it is necessary to give an answer which is – you do not. You cannot test if water is safe to drink. Do not even think of it. Real issues with any water in the wild is with the stuff that you cannot see.

So, water filter or water purifier? What to use?

From the text above it should be obvious that drinking glacier water directly should never be an option, regardless of how clean it may look.

In my view, it is best to use a mechanical purifier. This is the fastest way and the most convenient when you are on the go. You cannot always boil the water and do all the things that are recommended. Besides, it is not always only about micro-organisms, you want to remove physical particles as well.

But what sizes of pores do you need in a water filtering system? Let’s see some dimensions of micro-organisms.

  • Protozoa like giardia and cryptosporidium are around 10 microns, and 4-6 microns, respectively.
  • Bacteria like Escherichia coli are in the range 0.25 – 1 micron diameter. The smallest bacteria are practically always above 0.2 microns.
  • Viruses are usually in the range of 0.02 to 0.4 microns. The smallest virus is the Porcine circovirus type 1, and its diameter is only 0.017 microns. 

So if you want to be sure, your water filtering/purifying system should have pores below the numbers shown above. Most portable filters will not be safe enough.

But even if specifications tell you it has pores of 0.01 microns, can you trust them? The MSR Guardian Water Purifier is with pores that are 0.02 microns, so perhaps it could be safe. You will hardly find something better and more reliable. You can compare this with yet another great product, the Katadyn Pocket Water Filter with pores that are 10 times larger, i.e., 0.2 microns.

See more about the MSR Guardian Water Purifier in this video:


To summarize this text, I do not think that glacier meltwater is always safe to drink, so avoid using it directly if this is possible. There are many ultralight and backpack portable filters and purifiers, and I am convinced they are worth investment. If you have ever been on a melting glacier late in the season you will understand why I am saying this.

In short, go for a filter/purifier that has pores as small as 0.02 microns, and if possible equipped also with an activated carbon. This should work great against micro-organisms, impurities and particles, and harmful chemicals.

Check also my text about drinking rain water and about safety of personal water filtration systems. This site is all about outdoors questions and answers, and I add texts here on a regular basis, so bookmark it and keep as a reference.

Please use the comment box below in the case of questions or comments. Thank you for reading and have a nice day.

Me on Jalovec.Hi, I am Jovo, the founder of this OutdoorsFAQs site and several other outdoor sites. I have been mountaineering for almost 40 years already, and I have created this site to use as a reference for various questions that I receive in my sites. Being a theoretical physicist by profession, I tend to base my answers on facts and on my own personal experience.

Leave a Comment