Bottle caps are removed and discarded prior to the recycling of plastic or glass bottles and most refuse companies require you to remove the bottle cap before putting the bottle in your recycling box.
Plastic bottles are made from either polyethylene terephthalate (plastic #1) or high density polyethylene (plastic #2) but the plastic caps themselves can be made from high density polyethylene (plastic #2), low density polyethylene (plastic #4) or most often from polypropylene (plastic #5).
The polyethylene caps are the caps that you can deform easily if you squeeze or bend them with your fingers. These can be included with the plastic bottles in your recycling collection. An example of a polyethylene cap, is the flat cap commonly found on the top of plastic milk jugs. These caps push on to the top of the bottle rather than having a screw thread. Caps with a screw thread are usually made from polypropylene.
Polypropylene caps are much harder and more rigid than polyethylene caps, often with a screw on thread, and should not be included in your curbside recycling collection. If you try to bend these caps with your fingers the plastic will only bend a small amount. Polypropylene cap examples are detergent bottle caps, screw caps on soda, water bottles and toothpaste tubes or the flip top caps on shampoo bottles or other cosmetics products.
If you are not sure what type of plastic the cap is made from then place the cap in your general trash and recycle just the bottle.
Metal bottle caps are made from steel or aluminum with a polyethylene lining to prevent the metal from contaminating the liquid in the bottle. Metal bottle caps, commonly found on beer bottles should be removed from the beer bottle before the bottle is recycled.
There are privately run recycling schemes available for all New Jersey residents that will accept either plastic or metal bottle caps.
Details of these recycling schemes can be found below.
Metal Bottle Caps
Metal bottle caps and jar lids are made from steel with a polyethylene lining. Despite the plastic lining, the metal caps can still be placed in your recycling collection. Remove the caps from the glass bottles or jars and place them loose in your metal recycling container or commingled container. The plastic lining will be burnt off when the metal is processed to make new steel products.