The Charcoal Taste Filter: What It Removes, What It Grows, and the Replacement Interval Its Own Biology Imposes

SIMULATED, NOT MEASURED. A colonisation model of a granular activated carbon cartridge shows effluent heterotrophic counts rising from 5 to 794 CFU/mL by day 30, crossing 100 CFU/mL at day 10 — inside the rated 120 L life — imposing a 30-day calendar replacement rule; chlorine removal falls from 95% to 40% across the rating. Nothing was built or field-tested.