Activated carbon

Activated carbon is made from carbon-rich materials and „activated“ in a way that creates a dense network of extremely fine pores. Its internal surface is therefore exceptionally large. When water flows through, certain molecules attach to this surface. This is called adsorption – attaching to a surface, not soaking up like a sponge.

Chlorine and many organic compounds that cause smell and taste are bound well. Salts, nitrate and many metals, on the other hand, are bound poorly or not at all. Microorganisms are not reliably retained; in a moist, loaded carbon bed they can even multiply.

The effect is finite: once the surface is occupied, the carbon binds nothing more. You cannot see when that point is reached. Performance depends on carbon type, quantity, contact time and previous loading and cannot be checked in the field.

Activated carbon is ideal for improving the taste of water that has already been disinfected – for example after chlorination. It removes the chlorine taste and many unpleasant smells. As part of a tested system it can also reduce certain organic substances.

Many outdoor and household filters combine a membrane or ceramic with an activated-carbon part. It is important to understand who does what: the membrane or ceramic holds back the pathogens, not the carbon. The carbon takes care of taste and smell.

Activated carbon is unsuitable for disinfection, for desalination and as the only measure for water containing heavy metals, nitrate or unknown chemicals. If chemical contamination is suspected, another source is the right answer.

First settle microbiological safety: disinfect the water beforehand, or plan disinfection afterwards. Then pass the water slowly through the cartridge according to the manufacturer's instructions. The longer the water is in contact with the carbon, the better it can bind.

After chlorination, order matters: the chlorine's full contact time must have passed first. If you use the carbon too early, it removes the chlorine before it has made the germs harmless. Afterwards it removes the taste, but also the residual protection – the water should then be drunk soon or stored especially cleanly.

Note how much water you have filtered or how long the cartridge has been in use, and replace it as the manufacturer specifies. Do not wait until the water tastes bad – by then the carbon is long exhausted.

Activated carbon is not a disinfection method. Good looks, good smell and good taste say nothing about pathogens. Always disinfect water from nature – before or after the carbon – for example by boiling or chlorination according to instructions.

Campfire charcoal and barbecue briquettes are not activated carbon. Their effect is small and unknown, and briquettes may contain binders and other additives. They do not belong in a water filter, not even an improvised one.

Exhausted cartridges, or cartridges kept damp for a long time, no longer bind anything and can promote microbial growth. Follow the manufacturer's replacement interval and store cartridges as the instructions say.

A common myth says: „A carbon filter makes water clean.“ That is a dangerous misconception. Carbon makes water more pleasant, not safe. Precisely because the water tastes good afterwards, it tempts people to skip the actual disinfection.

A second myth: „Any charcoal filters.“ Ordinary charcoal has a much smaller and unknown internal surface. Activated carbon is made specifically to create this surface – without that process, the effect is largely missing.

In drinking-water treatment, activated carbon is a proven component against taste, smell and certain organic trace substances. Used correctly, it is a sensible addition – always together with a method that reliably makes pathogens harmless.