Whether Brita filters really give you better-tasting or cleaner water is a subject for debate, but most agree on one point—paying $5 or more for each 3-month replacement filter isn't very fun. But with a bit of time and the right supplies—a sharp utility knife (and/or drill), a cheap polyethylene plug, and an activated carbon mix from an aquarium store—you can refill an old filter over and over again for far less cost. The hardest part seems to be getting just the right size hole in the top of your filter; after that, you treat the refilled filters as if they were new. Thanks, Jamie!
How to refill a "disposable" Brita brand water pitcher filter with activated carbon. [Instructables]