Skip to main content

See also:

Leave those caps on your plastic bottles when recycling them!

Over the past 10 years, I have run into countless websites, blogs, and consumer comments/posts about how #1 plastic bottles (PET plastic) cannot be recycled if the bottle caps are left on them. As I am a man of science, I have decided it is time to bust the myth and debunk this ridiculous falsehood.

PET is the abbreviation/acronym for polyethylene terephthalate, an incredibly useful and environmentally friendly plastic. A large majority of drink bottles, including soft drinks, water bottles, sports drinks and some juice bottles are made of PET. Normally clear, it can also be colored, such as the green PET bottles that Mountain Dew(TM) is packaged in and the brown PET bottles used to package some brands of root beer.

PET has some very unique properties, including the ability to be recycled 100% and the ability to be sanitized to FDA food grade standards, thus allowing a used PET soft drink or water bottle to be recycled into a new soft drink or water bottle. Recycled PET, often abbreviated as rPET, can also be used to make synthetic fabric for use in clothing and also to make carpet fibers.

However, the caps that are used on PET bottles are commonly made from polypropylene (PP or #5 plastic) or high density polyethylene (HDPE or #2 plastic). While PP and HDPE are recyclable, the recycled material cannot be sanitized to FDA requirements for use in direct contact food packaging. PET, on the other hand, can be recycled 100% and can also be sanitized such that a used soft drink bottle can become a new soft drink bottle. Therefore, when a PET bottle with the cap still on it is ground up as the first step of the recycling process, it becomes contaminated with PP or HDPE plastic granules.

But not to worry! The next step in the PET recycling process is to wash the ground up plastic. This is where the myth will be debunked. The washing process also separates the ground up pieces of PET from the PP or HDPE quite simply. PP and HDPE plastic granules will float in water, but PET plastic sinks in water. By using a piece of equipment called a Sink Float Separation Tank, the PET can easily, simply, and cheaply separate from the bottle cap material.

A Sink Float Separation Tank is a specially designed tank that has skimmers that skim the top of the water and remove the PP and HDPE plastic. On the bottom of the tank, there are rakes (not the kind you use in your yard or garden) that scrape the PET plastic toward an auger that then removed the PET and sends it to the next phase of the recycling process.

As all PET plastic has to be washed when it is recycled, it can quickly be inferred that the stories of not being able to recycle PET bottles with the caps on are quite false. Any non-PET material will simply float and be skimmed off the surface of the water.

So go ahead and leave the caps on your soft drink, water, sports drink and other bottles and send them all to the recycling center. You won't be condemning that soft drink bottle to thousands of years in a landfill before it breaks down - you will actually be recycling two types of plastic at the same time, and helping the environment in doing so!