Leave the Caps Off!

by Bill Chameides | November 11th, 2008
posted by Erica Rowell (Editor)

Permalink | 3 comments

Remember to remove the cap and toss it before you recycle your bottles.

Are you an obsessive-compulsive type like me, who recaps plastic bottles before tossing them into the recycling bin? Wrong.

I was at a meeting recently where a friend of mine explained a growing recycling problem: many people screw the caps back onto their plastic bottle before recycling them. Apparently, not everyone realizes that this screws up the whole system: it adds unnecessary costs and may even foul the recycling stream.

So I did a small experiment and checked out a few nearby recycling bins. Sure enough, I found lots of plastic bottles with their lids on.

Different Plastic Types Require Different Reprocessing Methods

Recycling plastic bottles is a complex process. You see, all plastic bottles are not created equally. Their composition can vary significantly depending upon the type of resin used to make the bottle.

You probably know how to tell which type of bottle you have by looking at its base — the number inside the recycling logo tells you the bottle type. The vast majority of bottles are type 1 or 2. Type 1 is made of polyethylene terephthalate and is used for carbonated beverages and water. Type 2, made from high-density polyethylene (HDPE), is used for most milk containers. (And by the way, if you are worried, type 1 and type 2 do not typically use bisphenol-A (BPA) — type 7 is where you will most often encounter BPA; also be wary of hard, clear plastic. For more on spotting plastics with BPA, see here and here.)

Because each bottle is made from a different resin, each type of bottle has to be recycled separately to keep the batches chemically correct for the next generation of bottle. That means that when all those different bottles arrive at the recycling plant, someone has to sort them by hand, separating the type 1s from the type 2s and 3s, et cetera, before processing. Each bottle type generally requires a slightly difference process for recycling.

Because most bottles are type 1 and type 2, many locales recycle only these two types and toss the rest. In fact, in some municipalities like New York City, only type 1 and 2 are accepted for recycling –- you are instructed to recycle only plastic bottles and jugs, and throw the rest into the trash can. And here’s where plastic lids, caps, and tops come in. They and the bottles they seal are almost always made from different resins. In fact, it’s easy to tell if that is the case –- is the cap more rigid than the bottle? If so, then they are chemically different.

Because of the chemical difference, many recycling programs don’t even want your loose plastic lids, tops, and caps. They especially don’t want them attached to the bottle or container they once sealed. If they are attached, someone has to go through and laboriously unscrew lids from their bottles before processing. Is it possible that bottles with caps are simply tossed and not recycled in some recycling plants? If you know, please share.

There is another problem with recycled bottles with their caps on –- they can’t be crushed. As a result, they add to the volume of waste headed for the recycling plant and this adds to the cost.

So leave the caps off the bottles. And if you want to go the distance — follow the “wash and squash” rule — after you toss the cap, of course.

Additional Resource

EPA’s Energy Kid’s Page – Recycling –

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  1. Peter
    Nov 13, 2008

    Thanks for the post about removing the caps–I’ll certainly do so from now on. But that leads me to a concern–the caps are often not themselves labelled for recycling. Can we still recycle them separately? Also, is there anyplace I can find out what kinds of plastics certain common items are made of, e.g. different types of bottle caps (soda bottles, milk containers, etc.), bread bag tab closures, that hard-to-open packaging that small electronics often come in, etc.?” title=”Can we still recycle the caps separately?

    • wendy graber
      Nov 13, 2008

      Dr. Chameides responds – Peter, these are all good questions. Rigid bottle caps are often made from polypropylene (PP) or type 5 plastic. Please check with your local recycling outfit to find out what they accept–often there is a website that can provide this information. Where I live in NC, we are asked to put caps and lids in the trash. To counter this, one company Aveda has launched a nationwide effort to recycle bottle caps. You can access their program at to learn more. Additionally sometimes school groups or charities will also have local collection drives. And lastly, the link at the bottom of the post has a section that tells you which items are typically made from which plastics. Just scroll down. ” title=”Yes, but maybe with some extra effort.

      • Jason vonni
        Mar 10, 2009

        I have never once heard of this until this year, so I was recycling wrong this entire time? What’s so hard about putting a little notice on bins or bottles that says “Take off the cap before recyling.” You can’t magically expect people to know without telling them.” title=”What a joke.

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