We all know that plastic bottles are bad for the environment, but if you do use them, you recycle them. Right? But what about the plastic bottle caps?
Most plastic bottles are made from PET #1 plastic, but the caps are made from polypropylene, or plastic #5. Because these two types of plastics melt at different temperatures, they must be processed separately.
This has traditionally meant separating the cap from the rest of the bottle. If this was not done, the recycling equipment would either cause the caps to shoot off at a high speed, causing a safety hazard for the workers, or cause the bottles to retain air and take up too much space.
Recycling equipment has improved in recent years. The new equipment allows bottles with the caps on to be safely compressed and divided into separate plastic streams. Due to the small size of the caps, leaving them on the bottles causes the process to run more smoothly.
Whether or not you leave your bottle caps on depends on how new the recycling equipment is in your area. Check with your local center to see their rules. If in doubt, it is probably safer to leave the caps off.