Activated carbon is the most widely used filtration media in the world and for good reason. Its effectiveness comes from an extraordinary physical property: Its massive surface area.
A single gram of activated carbon has a surface area of up to 3,000 square metres — roughly half a football pitch, packed into a piece the size of a pea. This vast surface is what makes it so effective at trapping contaminants.
Adsorption, Not Absorption
Activated carbon works through a process called adsorption (with a "d," not a "b"). While absorption means soaking something up like a sponge, adsorption means binding molecules to a surface.
The carbon's microscopic pores create an enormous surface covered in binding sites. As water passes through, contaminant molecules are attracted to and held on the carbon surface by van der Waals forces - weak but persistent atomic-level attractions.
What Activated Carbon Removes
Carbon excels at removing organic and chemical contaminants:
- Chlorine — removed almost completely, eliminating the swimming-pool taste
- Trihalomethanes (THMs) — chlorine byproducts linked to health risks
- Volatile organic compounds — industrial solvents, fuel additives
- Pesticides and herbicides — agricultural chemical residues
- Pharmaceutical traces — many drug metabolites are captured
- Taste and odour compounds — musty, earthy, or chemical flavours
What It Doesn't Remove
Carbon has limitations. It's less effective against:
- Dissolved heavy metals (lead, mercury) — these require ion exchange
- Bacteria and parasites — these need membrane filtration
- Dissolved salts and minerals — these pass through (which is actually desirable)
- Some short-chain PFAS compounds — these may need additional treatment
This is why effective water filters combine carbon with other technologies. Each medium handles what it does best — carbon for chemicals, ion exchange for metals, membranes for particles.
Block vs. Granular
Not all carbon filters are equal. The two main forms have very different performance characteristics:
Granular Activated Carbon (GAC)
Loose granules packed into a cartridge. Water can find channels between granules, reducing contact time and filtration effectiveness. Common in basic jug filters and shower filters.
Carbon Block
Compressed carbon powder sintered into a solid block. Water is forced through the entire block, ensuring maximum contact time and consistent filtration. Significantly more effective than GAC, but more expensive to manufacture.
Why Coconut Shell Carbon?
Carbon can be made from various source materials such as coal, wood, peat, or coconut shells. Coconut shell carbon produces the most consistent pore structure, with a higher proportion of micropores ideal for trapping small organic molecules. It's also a renewable, sustainably sourced material a meaningful advantage over coal-based carbon.
