Do the filter cartridges expire?
No. The cartridges have an unlimited shelf life as long as they are kept dry. For this reason, we recommend purchasing a Super Value package, which offers you an additional discount on each filter.
When replacing the cartridge, does it matter which side faces the wall?
The SLC cartridge has one end that's flat and one end that's "recessed." The recessed or cup end side should face the wall so water will enter into the cup end side and exit the flat end.
Has Sprite changed the casing style for their replacement filters?
Yes, they have and they may do so again in the future. Sprite uses two types of casings: white and clear.