Water purifier. Scanning electron micrograph (SEM) of the components of a commercial household water filter. Activated charcoal (yellow) filter mixed in with ion-exchange resin beads (blue). The activated carbon filter eliminates bad odor and the taste of halogen compounds that chlorine makes when present in tap water. The exchange ion resin lowers the concentration of calcium carbonates, accordingly softening tap water. Magnification x 26 at 10cm wide.