In Sarek you rarely lack water — more often you lack reflection on which water to choose. After years of leading groups in Swedish Lapland I know that a bottle filled in the wrong place can end an expedition faster than soaked boots. Water is everywhere here: in streams, in lakes, in snowfields, on bogs. The art is to pick from this abundance a source that will not put you down with a fever in your tent the next day.
How to assess water before drinking
Before I reach for the filter, I first look. Colour and smell say more than one might think, and in the field they are often the only information you really have at hand.
Clear water, without a distinct smell, with a well-visible current, is candidate number one — such water I collect without much hesitation, of course after filtration. Cloudy, milky, greyish water most likely carries glacial dust, so it is suitable for treatment, but only after prefiltration through a piece of cloth, or it has to settle first for several hours. Brown, tea-coloured water with an earthy taste is usually water from peat bogs; after filtering or tablets it is also suitable for drinking, although you have to accept the fact that tea made on such water will never look and taste appetising.
There is, however, one sight at which I simply walk away. A green or blue-green skin on the surface, water looking like spilled oil paint or like green jelly — these are cyanobacteria. They produce cyanotoxins, which no field filter or chlorine tablet will remove, and boiling will not help either, because these toxins are thermostable, meaning high temperature does not destroy them. The only decision I make there is to change the source, even if it means an extra half hour of walking with empty bottles.
Where to take water from in Lapland
The best water in Sarek flows in the upper sections of streams, high above the valley, above the places where reindeer graze. This is my basic rule — I go up for as long as it takes until I see that the herd has been left behind me. Reindeer leave parasites in the water, mainly Giardia and Cryptosporidium, microscopic organisms from droppings, which can take a person out of marching for several days of diarrhoea and stomach pain.
Standing water I treat with great caution. Lakes near the shore, where nothing moves the water, and also all kinds of bogs and wetlands are places where pathogens have time to concentrate. If I have to draw from a lake, I move a little away from the shore and take from deeper, moving water, ideally from the side from which some stream flows in.
A separate topic is glacial dust, that famous glacial flour. Streams from under glaciers can be cloudy, milky, sometimes almost grey. The dust itself is not dangerous to health — it is simply finely ground rock — but it can clog a membrane filter with a dense mesh inside, sometimes after just one filling, if the water from under an active glacier is very turbid. If there is no other water in the area, I prefilter such water through a piece of clean cloth — a scarf, a bandana, a fragment of a T-shirt — before it reaches the proper filter, or I leave it in a folding bowl for a few hours so that the dust settles to the bottom.
What I use to treat water — my set
After years of trying I have arrived at a simple, light set that I take on every expedition to Sarek. Nothing in it is accidental, but nothing is sacred either — it is simply a compromise that works best for me.
The base is a Sawyer-type filter, the squeeze kind. Light, fast, it stops bacteria and protozoa, including Giardia. I use it for the vast majority of fillings. In Sarek the viral risk is negligible — few people, clean nature — and that is why the filter alone is fully enough. In other regions of the world, where the density of people is greater, the approach can be different, and it does not hurt to think it over before the trip.
The second element is chlorine tablets, but I use them as a backup, when the filter freezes, breaks or gets clogged with glacial dust. Here one important note: in cold water, that is below ten degrees, and in Sarek this is the standard, the tablets work much more slowly. Instead of the usual fifteen minutes I wait half an hour, sometimes even a whole hour. I do not treat the tablets as a quick replacement for the filter, because in winter boiling is simply faster and more reliable.
The third thing is boiling. With the evening meal I am heating water for soup or tea anyway, so a minute of boiling takes care of pathogens and gives me peace of mind at supper.
I carry the tablets separately, in the side pocket of the backpack, not together with the filter. Should anything happen to the main piece of equipment, I do not want to lose both things at once. And one more thing, easy to forget: a Sawyer filter after freezing is fit only to be thrown away, because its membrane cracks. So in the evening I hide it in the sleeping bag or in the inner pocket of the jacket, close to the body.
How much water and when to drink
In Sarek, with active marching, I usually drink three or four litres a day. Cold can mask thirst and it is easy to miss the fact that the body is calling for water. That is why I drink rather out of habit than out of thirst — a sip every few tens of minutes, regardless of the weather. The signs that it is already too late are quite legible: a headache, dark urine, irritability, reluctance to eat. The answer to each of them is the same — have a drink and slow down.
Mistakes I have seen on the trail
Three situations keep returning in my memory, because they ended in problems in front of my eyes.
The first is drinking straight from a lake without filtration, because „the water looks clean”. Giardia has neither smell nor colour, and a person learns about it only after two days, when he is already far from civilisation.
The second is drawing from a stream below a reindeer pasture. It is always worth looking at what is happening a hundred metres higher up, before filling a bottle.
The third is using chlorine tablets in icy water after fifteen minutes, as written on the packaging. In cold water the reaction is simply slower, and the shortened time is a fiction of safety.
Water in Sarek is a gift, not a problem. It only has to be treated with the same attentiveness with which one chooses boots for an expedition. Before you pack the backpack: a filter, tablets in a separate pocket, a bottle of at least one litre per person — and the knowledge of the difference between a stream above and below a pasture.
Back to tips