Water can look completely clean and clear, but still contain bacteria, viruses, or parasites that you cannot see with the naked eye. Furthermore, if just one person in the group falls ill, an entire trip or hike can be affected. Problems caused by contaminated water can make it difficult to continue moving, and it can take several days, sometimes longer, before one feels well again.

If you don't have a ready-made water purification solution with you, there are several simple steps you can take to reduce the risk.

Start by choosing the best possible water source

The choice of water source is important, but even good water sources may need to be treated.

Preferably choose:

• running water over stagnant water
• water as far upstream as possible
• water far from paths, animals, and settlements

Avoid water that smells bad, is discolored, has algal blooms, or looks clearly affected.

A clear, flowing stream is generally a better choice than stagnant and murky water, but its appearance does not indicate whether the water is microbiologically safe.

Water purification step by step

If the water is cloudy, you can first let it stand for a while so that particles sink to the bottom.

1. Choose the best possible water source.
2. Let cloudy water stand so that particles can sink.
3. Carefully pour off the clearer water and pre-filter through clean cloth, coffee filter, or other suitable filter.
4. Then boil or treat the water.
5. Store the treated water in a clean container.

Pre-filtering primarily removes particles. It does not automatically make the water safe to drink.

Boiling is an important backup method

When you are unsure of the water quality, boiling is an important method.

Bring the water to a rolling boil. Then let the water cool in a clean jug, bottle, or other clean container.

Boiling helps against bacteria, viruses, and parasites. However, boiling does not remove chemical contaminants, salt, or heavy metals, for example.

A simple emergency filter can make the water clearer

If the water contains many visible particles, a simple filter can be used for pre-treatment.

You can, for example, use clean cloth or a coffee filter. A simple layer filter can also be built with materials such as sand and gravel to trap dirt and visible particles.

However, a homemade filter should always be considered pre-filtration. It needs to be followed by boiling or other appropriate treatment. A simple filter does not automatically make the water safe.

Avoid common mistakes

Do not drink water simply because it looks clear.

Avoid:

• stagnant water
• water near animals, paths, and settlements
• water with an unusual smell or discoloration
• water with algal blooms
  

Even mountain water, spring water, and melted snow may need to be treated before drinking.

If the municipality recommends boiling tap water

If there is suspicion of bacteria, viruses, or parasites in the municipal drinking water, the municipality may issue a boiling recommendation.

In such cases, water intended for drinking or use in food preparation should be boiled until it bubbles vigorously. The boiled water should then cool in a well-cleaned container.

Boiled water should be used for, among other things:

• drinking
• coffee
• ice
• rinsing fruit and vegetables to be eaten raw
• toothbrushing
  

Unboiled water can normally be used for things like food that will be cooked anyway, handwashing, showering, washing dishes, laundry, cleaning, and flushing toilets, according to the municipality's and the Swedish Food Agency's current recommendations.

When you can, be prepared

The simplest thing is to plan ahead and have a proven solution with you in your pack, on your trip, or at home.

FreeBact® Water is developed for the disinfection of drinking water. For FreeBact® Water Drink, according to the product's instructions for use:

• inactivates viruses, bacteria, and fungi
• 5 times more effective than chlorine products
• leaves no taste
• easy dosing, 1 drop per dl of water, wait 1 minute
• 50 ml is enough for 50 liters of safe water
  

Chlorine dioxide is approved as a drinking water additive by the Swedish Food Agency.

Filtration means that particles and, depending on the filter's pore size, certain microorganisms are physically removed from the water. Disinfection means that microorganisms are rendered harmless, for example by boiling, UV light or an approved disinfectant. For cloudy or unsafe natural water, a combination of filtration and subsequent disinfection is often best.

Always follow the municipality's current information. Boil all water intended for drinking or cooking until it bubbles vigorously. Boiled water should also be used for things like coffee, ice, brushing teeth, and rinsing fruit and vegetables that will not be cooked. Store the cooled water in a clean jug, bottle, or other container.

Boiling kills or inactivates bacteria, viruses, and parasites. The microorganisms are therefore not filtered out, but are neutralized by the heat. However, boiling does not remove grit, salt, heavy metals, fuel, or most other chemical contaminants.

No, not without knowing the water quality. Even clear water from a mountain stream can contain bacteria, viruses, or parasites from humans and animals. Therefore, boil or treat the water before you drink it.

No, melted snow should not be considered automatically safe drinking water. The snow may have been contaminated by animals, people, or particles from the surroundings. Melt it first and then treat the water in the same way as other untreated natural water. Do not eat snow directly to hydrate yourself, as the body will then have to use energy to melt and warm it.

Running water is often a better choice than stagnant water, but it is not automatically safe. Ideally, choose water near the source and upstream from paths, settlements, grazing animals, and campsites. Even running water should be treated before drinking.

No. A clean cloth or coffee filter can trap grit, plant debris, and other visible particles but will not reliably remove bacteria, viruses, or parasites. Pre-filtering must be followed by boiling or an appropriate disinfection method.

Not reliably. A filter with fabric, sand, and gravel can make the water clearer, but it is not designed or tested to safely remove disease-causing microorganisms. The water must therefore be boiled or disinfected after filtration.

Yes, but it's best to let the water sit first so that the particles can settle. Carefully pour off the clearer water and pre-filter it through a clean cloth or coffee filter before boiling. Boiling can inactivate microorganisms even in cloudy water, but pre-filtering makes the treatment easier and more effective.

Store the water in a well-cleaned container with a tight-fitting lid. Preferably use a container with a narrow opening, so that hands or objects do not need to be submerged in the water. Store it in a cool place, protected from direct sunlight and away from fuel, pesticides, and other chemicals.

No, not with regular boiling, filtering, or disinfection. Water that smells of fuel, solvents, or other chemicals should not be used as drinking water. Instead, choose another water source or use controlled drinking water, as harmful chemicals and heavy metals may remain after treatment.