Water filters contain activated charcoal and after mine expire I cut open the cartridge (CAREFULLY with a steak knife) and pour the contents into my cats' litter box to reduce odor. I could also use it in my chicken coop for the same reason.
Donna here again...Just wanted to mention that i actually left the charcoal in the pictured foil pan and placed it in my oven (after cooking dinner) to totally dry the granules out before putting into the litter box, btw!
