Since plastic degrades over time and the bottle has to withstand recurring pressure from carbonation, it cannot be used forever. The expiration date on the bottle must be checked and new bottles purchased as soon as the former expires. The plastic bottles must also be replaced if put in the dishwasher, exposed to a heat source, or if they have become scratched. All components of carbonating bottles except for the seal inside the cap are recyclable. Check with your local recycling authority for more information.