system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 How does charcoal filter out stuff from water?
gpt
Besides normal old filtering by catching big stuff like a net, activated charcoal has tiny pores in it. The tiny holes grab up stuff in the water and entrap it. Eventually the holes get filled up and it doesn't work so well so you need a new filter.  One gram of the stuff can have a surface area of 3,000 square  meters according to wikipedia. That's nearly half a football field. Lot's of little holes for stuff to get caught in.