Kitchen Plastic Sorting by Resin Code: A Room-by-Room Walkthrough

Start With the Number, Not the Color or Shape

Before any plastic touches your recycling bin, turn it over and look for the chasing-arrows triangle with a number from 1 to 7 inside. That number is the resin identification code, and it tells you the plastic type. In most curbside programs, only certain numbers are accepted, and the rule is not about color, brand, or whether the container once held food. It is about the polymer itself, because each type melts and reprocesses differently.

For kitchen sorting, focus on the three most common resin codes you will see on food packaging: 1 (PET or PETE), 2 (HDPE), and 5 (PP). Codes 3, 4, 6, and 7 are less frequently recycled through household bins, and many municipalities exclude them due to low demand or contamination risk. Check your local hauler's website or app to confirm which numbers they collect, because acceptance varies widely by region and even by neighborhood.

A quick note: the presence of a number does not guarantee recyclability. A yogurt cup marked with a 5 might be recyclable in one city but not another, depending on local sorting equipment and end markets. When in doubt, treat the number as a starting point, then verify against your curbside guide. If your program uses single-stream recycling, also check whether caps and lids should be reattached or removed—this differs by facility.

Resin 1 and 2: The Backbone of Bottle Recycling

Resin 1 (PET) is the plastic of clear beverage bottles—water, soda, and some juice containers. It is also used for single-use salad dressing and peanut butter jars. Resin 2 (HDPE) is the opaque, sturdier plastic found in milk jugs, detergent bottles, and many shampoo containers. In most curbside programs, these two are the most reliably accepted because they have well-established end markets, often being turned into new bottles, carpet fiber, or strapping.

For kitchen sorting, this means your empty water bottles, soda bottles, and milk jugs are almost always safe to place in the bin, provided they are empty, rinsed, and have their caps on (check local rules). One exception: bottles that contained cooking oil or greasy condiments may need extra rinsing to avoid contaminating the batch. If a bottle is too greasy to clean, it belongs in the trash, because a single dirty item can ruin an entire bale.

A common mistake is assuming that all bottles are equally recyclable. For example, a clear PET water bottle is highly recyclable, but a dark-colored PET bottle (like some sports drinks) may be less valuable to recyclers because the dark plastic is harder to sort. Similarly, HDPE comes in natural (white) and colored forms; natural HDPE is more valuable. Always empty and rinse, but do not crush bottles excessively—some facilities use optical sorters that need to recognize the shape.

Resin 5: The Flexible Workhorse of Containers and Tubs

Resin 5 (polypropylene) is the plastic of many rigid kitchen containers: yogurt cups, margarine tubs, sour cream containers, and some reusable food storage lids. It is also used for bottle caps (like those on soda bottles) and some straws. PP has a higher melting point than PET or HDPE, which makes it suitable for hot-fill items and microwavable containers, but that same property also means it needs a different recycling process.

In recent years, more curbside programs have started accepting resin 5, but it is still not universal. If your hauler accepts it, the rules are usually the same as for other rigid plastics: empty, scrape out food residue, and rinse. However, be cautious with tubs that have foil or paper labels—peel off what you can, because labels can contaminate the plastic flake. Also, do not assume that a 'microwave-safe' symbol means the container is recyclable; that symbol refers to heat resistance, not recyclability.

A particular challenge with resin 5 is the difference between rigid and film forms. A rigid PP yogurt tub is often recyclable, but a PP film (like the wrapper on a pack of crackers) is usually not, because it tangles in sorting machinery. If your plastic is flexible and can be scrunched into a ball, it is likely a film and should be excluded unless your program specifically collects plastic bags and films. Check with your local store drop-off if you have clean, dry film.

Resins 3, 4, 6, and 7: What to Do With the Less Common Codes

Resin 3 (PVC) appears in some cling wraps, squeeze bottles, and older food trays, but it is rarely recycled curbside because it releases harmful chemicals when melted. Resin 4 (LDPE) is the plastic of many bread bags, produce bags, and some squeezable bottles—it is technically recyclable, but usually only through store drop-off programs, not curbside bins. Resin 6 (polystyrene) is the foam and rigid plastic of disposable cups, takeout clamshells, and egg cartons; it is lightweight and often not cost-effective to recycle. Resin 7 is a catch-all for mixed plastics, including polycarbonate and bioplastics; most curbside programs reject it.

For kitchen sorting, the practical rule is: if it is not a 1, 2, or 5 (and sometimes 4), treat it as trash or check for specialized drop-off. Foam takeout containers, plastic wrap with a clingy feel, and any container labeled with a 3 or 6 should go in the landfill bin. Some communities have special events for polystyrene, but these are rare. Do not place these items in your curbside bin hoping they will be sorted out—contamination can cause the entire load to be sent to landfill.

One exception to the 'check the number' rule is compostable or bioplastic containers, which are often labeled with a 7 but may have a 'PLA' or 'compostable' stamp. These should never go in the recycling bin because they can disrupt the recycling stream. Instead, they belong in your compost pile (if you have one) or the trash. If you are unsure, the safest bet is to look for the chasing arrows symbol and the number, then cross-reference with your local guide.

A Worked Example: Sorting a Week of Kitchen Plastics

Imagine you are cleaning up after a week of meal prep. Your counter holds: a clear water bottle (resin 1), a milk jug (resin 2), a yogurt cup with a foil lid (resin 5), a plastic takeout clamshell (resin 6), a plastic bread bag (resin 4), and a squeeze bottle of honey (resin 1, but with a flip-top cap). Here is how you would sort them step by step.

First, set aside the water bottle and milk jug—they are clearly resin 1 and 2. Rinse them out, remove the cap (check local rules: many facilities want caps reattached, but some want them removed), and place them in the bin. Next, handle the yogurt cup: scrape out the remaining yogurt, rinse it, and check if the cup is marked with a 5. If yes, and your program accepts 5, put it in the bin. If not, it goes to trash. The foil lid is not recyclable—tear it off and throw it away.

Now the clamshell: it is resin 6, so unless your program specifically accepts it, place it in the trash. The bread bag is resin 4; if it is clean and dry, you could take it to a store drop-off for plastic film, but do not put it in your curbside bin. Finally, the honey bottle is resin 1, but it is sticky—rinse it thoroughly, and if the cap is a different plastic (often resin 5), decide based on your local rules. If you cannot clean it, trash it. The key takeaway: sort by number, but also by cleanliness and local acceptance, and when in doubt, throw it out.