The number inside the triangle is a resin identification code. It tells a sorting facility what polymer an item is made from and says nothing about whether anyone collects it. The clearest proof is that a plastic bottle and a plastic clamshell can both carry a number 1 and have completely different fates: in a recent year about 27 percent of PET bottles were recovered against roughly 9 percent of thermoformed PET. Same resin, same code, opposite outcome. From October this year, California treats the symbol itself as a claim that must be true.
Once you understand why those two items diverge, the whole labelling system makes sense.
What the code actually is
The system was created to help processors identify polymers, not to instruct households. The number identifies chemistry. Three other things decide whether an item is recycled:
- Form. Bottles sort easily; flat, thin or oddly shaped items do not.
- Colour and additives. Opaque, black and multi-layer versions of a recyclable polymer often are not.
- Local market. A material with no buyer near you is not collected, whatever it is made of.
That is why guidance from every serious source ends with check locally, and why a code alone has never been enough.
The seven codes, and what each is really worth
| Code | Polymer | Typical items | Collection reality | |
|---|---|---|---|---|
| Measurement | What it is and how widely it is taken | |||
| 1, PET | Polyethylene terephthalate | Drink bottles, jars, clamshells, trays | Bottles accepted almost everywhere; thermoforms patchy | |
| 2, HDPE | High density polyethylene | Milk jugs, detergent and shampoo bottles | Widely accepted; splits into higher-value natural and lower-value coloured | |
| 3, PVC | Polyvinyl chloride | Pipe, some blister packs, cling film | Essentially never collected kerbside | |
| 4, LDPE | Low density polyethylene | Carrier bags, film, squeeze bottles | Film goes to store collection only, never kerbside | |
| 5, PP | Polypropylene | Tubs, lids, cutlery, some hangers | Accepted in many programmes, refused in many others | |
| 6, PS | Polystyrene | Foam packaging, cups, disposable cutlery | Almost never collected | |
| 7, Other | Everything else, including bioplastics and polycarbonate | Multi-layer packaging, PLA cutlery | A catch-all, effectively never recycled |
One surprise in the data is worth flagging. HDPE bottle recycling has been measured at 29.3 percent, essentially level with PET bottles, against a common perception that it recycles at half the rate.
HDPE also demonstrates the colour point precisely. Facilities split it into two streams that sell at different prices: natural HDPE, the translucent milk and water jug material, which commands the higher price and can return to food-contact use, and coloured HDPE, which goes into pipe, garden furniture, decking and non-food bottles.
The deepest problem: same number, opposite fate
A bottle and a clamshell
Both are PET. A bottle is blow moulded; a clamshell is thermoformed. That manufacturing difference changes everything downstream.
Sorting lines were built and calibrated for the shape and density of bottles, running material past optical sorters at speed. A clamshell is flatter, lighter and far more variable in size, so historically it was either misrouted into a mixed-plastic bale or discarded.
There are two further complications. Lookalike polymers, particularly polystyrene and PVC, resemble PET thermoforms closely enough to threaten contamination for reclaimers. And thermoforms had no centralised industry backing comparable to the beverage sector's promotion of bottles.
The industry bale specification quantifies the caution exactly: a PET bottle bale may contain thermoforms above 2 percent but not exceeding 10 percent by weight. That single line is the clearest statement anywhere of how the system regards the two items.
The position is improving. Access to programmes accepting thermoformed PET has reached 54 percent of US residents, and collection in the US and Canada hit a record 264 million pounds in the latest reported year, a 52 percent rise, though better data collection contributed to that figure.
But recovery and circularity are not the same thing. In that same year recycled content in new thermoforms fell from 18 percent to 12 percent, with virgin resin making up 79 percent of the 2.05 billion pounds of feedstock purchased. More is being collected; less of it is going back into the same product.
Colour, layers and additives
A polymer can be disqualified without changing its code.
Multi-layer lamination, opaque and black PET, optical brighteners and oxygen barrier additives cannot be separated from the base resin, so they contaminate the recycled stream rather than joining it. The package still carries a number 1.
This is the mechanism behind most household confusion. People compare the number on two items, see the same digit, and reasonably assume the same answer.
The symbol is now a legal claim
The most significant change in this area is regulatory rather than technical.
What California requires
A state law treats the chasing arrows symbol, the chasing arrows surrounding a resin code, or any other indicator of recyclability as a deceptive claim unless the item genuinely qualifies.
To qualify, a product or packaging must be collected by kerbside programmes serving at least 60 percent of the state's population, be accepted and processed in more than 60 percent of the state, show demonstrated commercial demand, and routinely become feedstock for new products.
The state waste agency published the underlying material characterisation study in April last year, and the restrictions apply to products manufactured after 4 October this year. The study is to be revised in two years and every five years after, with manufacturers given 18 months to adjust each time.
Recordkeeping obligations are already live: any company making an environmental marketing claim must hold written documentation supporting it and provide it to any member of the public who asks.
The conflict, and the challenge
This creates a genuine legal tangle rather than a clean improvement.
More than 35 states require certain plastic packaging to carry a resin identification code with chasing arrows. One state imposes a $500 civil fine per violation for omitting it. A manufacturer can therefore comply in California by removing the arrows and fall out of compliance elsewhere by doing so.
The law is also being challenged in court on constitutional grounds relating to commercial speech, and the outcome could reshape or strike parts of it. The compliance date currently stands regardless.
How to read a package properly
- Read the number as chemistry, not as an instruction.
- Look at the form. Bottle and jug shapes are the safest bet in any programme.
- Check colour. Clear beats coloured, and black is frequently invisible to optical sorters.
- Ignore vague words. Biodegradable without a named certification means nothing.
- Check your own programme's list. It overrides everything above.
- When in doubt, leave it out. A wrong item in the bin costs more than a right item in the waste.
Where this fits
Why shape defeats sorting lines is explained in our pages on disposable cutlery and bagged recycling. Why film has its own separate route is covered on the plastic film page, and the relationship between end markets and collection rates runs through what actually gets recycled.
How we produced this
Recycling and recovery rates for PET bottles and thermoforms, the collection tonnage, the access percentage and the recycled content figures come from the trade association that tracks PET container recovery in North America, reported through its annual analyses and trade press coverage of them. The bale specification threshold is from a published industry model specification.
The HDPE bottle rate is from the most recent finalised federal municipal waste figures. Sorting behaviour and contamination mechanisms are described from published material recovery facility and reclaimer guidance.
The labelling law provisions, qualifying criteria, compliance date and conflicting state requirements are taken from the statute, the state agency's published guidance and legal analyses of it. The constitutional challenge is ongoing and we have described it as such rather than predicting an outcome.
Frequently asked questions
Does the number inside the triangle mean an item is recyclable?
No. It is a resin identification code that tells a processor which polymer the item is made from. Whether anyone collects it depends on the item's form, its colour and additives, and whether a buyer exists near you.
Why is a plastic bottle recycled but a clamshell with the same number is not?
Because the manufacturing differs. A bottle is blow moulded and a clamshell is thermoformed, and sorting lines were built and calibrated for the shape and density of bottles. In a recent year about 27 percent of PET bottles were recovered against roughly 9 percent of thermoformed PET.
Are clamshells becoming more recyclable?
Access is improving. Programmes accepting thermoformed PET now serve about 54 percent of US residents, and collection reached a record 264 million pounds in the US and Canada in the latest reported year. But recycled content in new thermoforms fell from 18 percent to 12 percent over the same period.
How much thermoform is allowed in a bottle bale?
The industry model specification permits thermoforms above 2 percent but not exceeding 10 percent by weight of a PET bottle bale. That threshold is the clearest single statement of how the recycling system regards the two items differently.
Why does black plastic cause problems?
Optical sorters identify polymers by their infrared signature, and black pigments absorb the light rather than reflecting it, so the item is frequently invisible to the machine. Opaque, multi-layer and additive-modified plastics create similar problems without changing the resin code.
Which numbers are actually collected?
Codes 1 and 2 in bottle and jug form are accepted almost everywhere. Code 5 is accepted in many programmes and refused in many others. Codes 3, 6 and 7 are essentially never collected kerbside, and code 4 film goes to store collection rather than a bin.
Is it true that HDPE recycles at half the rate of PET?
No, that is a common misconception. The HDPE bottle recycling rate has been measured at 29.3 percent, essentially level with PET bottles. HDPE does split into two streams at different prices, with natural jugs commanding more than coloured material.
Is the recycling symbol being banned?
Restricted rather than banned. California treats the chasing arrows, or arrows around a resin code, as a deceptive claim unless the item is collected by programmes serving at least 60 percent of the state population, processed in more than 60 percent of it, and has demonstrated commercial demand.
When does that take effect?
The restrictions apply to products and packaging manufactured after 4 October this year, eighteen months after the state agency published its material characterisation study. Recordkeeping obligations are already in force for any environmental marketing claim.
Do other states require the opposite?
Yes, which is the awkward part. More than 35 states require certain plastic packaging to display a resin code with chasing arrows, and one imposes a $500 civil fine per violation for omitting it. The California law is also facing a constitutional challenge over commercial speech.