Why Activated Charcoal Water Filters Are So Effective
June 30, 20212 min read
Activated charcoal (activated carbon) is the most widely used filtration media in home water filters — and for good reason. Here’s a clear explanation of how it works and what it removes.
Activated charcoal is carbon that has been treated with oxygen at high temperature to create millions of microscopic pores. This process dramatically increases the surface area — a single gram of activated carbon can have a surface area of 300–2,000 square metres. That enormous surface area is what makes it so effective at trapping contaminants.
The key mechanism is adsorption (not absorption). Contaminants bond chemically to the carbon surface as water passes through, becoming permanently trapped. The carbon doesn’t dissolve or release these compounds back into the water.
What Activated Carbon Removes
Contaminant
Effectiveness
Chlorine
Excellent — removes 95%+
Chloramines
Good (catalytic carbon is more effective)
VOCs and pesticides
Good — bonds to organic compounds
Taste and odour compounds
Excellent
Disinfection by-products (THMs)
Good
Heavy metals
Limited (KDF media is more effective)
Fluoride
Not removed
Bacteria and viruses
Not reliably removed
Activated carbon retains beneficial minerals (calcium, magnesium, potassium) — it selectively traps chemical contaminants while allowing minerals to pass through.
Carbon Block vs Granular Activated Carbon (GAC)
Carbon block: compressed carbon in a solid block. Water is forced through the entire block, maximising contact time and contaminant removal. Better performance at equivalent flow rates. Used in most quality under sink and benchtop filters.
Granular activated carbon (GAC): loose carbon granules in a housing. Water can channel through gaps between granules, reducing contact time. Lower cost; used in whole house systems where flow rate is the priority.
Frequently Asked Questions
How long does an activated carbon filter last?
Typically 4–6 months for a whole house carbon cartridge; 6–12 months for a benchtop or under sink carbon stage. Replace when chlorine taste or smell returns, or when water pressure drops. Browse our replacement cartridge range.
Can activated carbon filters be regenerated?
No — once the bonding sites on the carbon surface are full, the filter is exhausted and must be replaced. Unlike some filter media, activated carbon cannot be backwashed or regenerated at home.
What’s the difference between activated charcoal and activated carbon?
They’re the same thing — “activated charcoal” and “activated carbon” are used interchangeably. Both refer to carbon that has been treated with oxygen to create a highly porous structure for adsorption.
Subscribe
Sign up to get the latest on sales, new releases and more …
