We’ve all been there. You just threw a big house party, or spent the night in with the family and polished off the last few delicious slices of your favorite pie. Now you’re wondering, what am I going to do with these huge cardboard boxes?

It’s a question that has vexed even the brightest pizza-loving minds for generations, or at least since the invention of the modern corrugated cardboard pizza box in the 1960s. It’s not a small one, either. According to a 2020 study by packaging manufacturer WestRock, Americans go through an estimated three billion pizza boxes annually, which equates to roughly 600,000 tons of cardboard.

With this constant stream of pizza boxes flying off the shelves and into dining rooms, it’s important to know whether or not these pristine vessels of cheesy goodness can be recycled. Just as no one would want a perfectly good pie to go to waste, no one wants to throw a perfectly reusable pizza box in a landfill.

But for many Americans, guidelines from their local waste collection service can send mixed signals when it comes to disposing of pizza boxes. While some collection services happily accept them into the recycling stream, others don’t . Many services don’t explicitly mention pizza boxes but accept cardboard generally, so it’s no wonder there’s so much confusion over what to do after the pie is gone.

So, can used pizza boxes be recycled? It all depends on where you live and how dirty the box is.

But before we can get to the specifics of how to deal with your used pizza boxes, let’s take a quick step back to look at how cardboard is actually recycled.

How is Cardboard Recycled?

The process starts exactly where you think: When you break down cardboard packaging and place it in your curbside recycling bin, it gets collected by your local waste management service and delivered to a nearby recycling facility.

That’s where each inbound cardboard product is sorted and screened for contaminants, like plastics, grease or food scraps, before being piled and compressed into giant bales.

Cardboard typically makes up a sizable share of the items that reach any given recycling center. At Recology’s 200,000 square-foot recycling facility in San Francisco, for example, paper and cardboard account for about a quarter of the 450 tons of recyclables it processes every day, roughly on par with the national average .

Waste servicers then ship the bales of cardboard to paper mills, where this “feedstock” is shredded and fed into large pulping machines that use warm water and constant mixing to break down the material into a thick, fibrous paste. That paste is sent through a series of filters designed to remove extraneous substances such as plastic, ink and metal staples to get pure paper fiber.

Finally, the wet fibers are pressed, dried and rolled into giant spools (or reels) of paper that are ready for use by manufacturers to make new cardboard packaging, including the corrugated cardboard our pizza is usually delivered in.

This entire circular process is quite efficient. According to the American Forest and Paper Association , the cardboard recycling rate was 93% in 2022, making it the “most-recycled packaging material in the U.S..”

Why Can’t Some Pizza Boxes be Recycled?

So, knowing all that, can pizza boxes really be recycled? The short answer is yes, but it gets complicated with the messier, greasier pies.

That’s because paper mills require clean feedstock with few impurities to effectively create new paper out of recycled cardboard. That means cardboard that is almost entirely free from food scraps, grease and other contaminants like styrofoam and plastic. If it isn’t, it could interfere with the pulping and filtering processes described above, and lead to impure fibers that won’t bind to make paper.

“Paper mills that utilize bales of recycled cardboard to make new cardboard require high-quality bales,” Robert Reed, public information officer at Recology, said in an emailed statement. “Mills want clean, dry recycled cardboard. Mills say cardboard that is despoiled with grease or food remnants cannot be recycled in their processes.”

The good news is, the standard cheese or veggie pizza probably won’t cause enough of a mess to soil the box it’s delivered in. Those loaded meat lover’s or super-saucy barbecue chicken bacon pies, on the other hand, are much more likely to leave behind big grease stains.

Some restaurants have added sheets of wax paper or other kinds of thin barriers to maintain the integrity of their delivery boxes, and they’re usually effective at keeping the boxes clean and recyclable. But if you’re ordering a greasy pizza from your local joint that doesn’t come with wax paper, it’s probably best to keep that box out of the recycling.

So, What Should I Do with Used Pizza Boxes?

Again, the answer to that question will depend on how messy they are, as well as your city’s specific recycling guidelines.

As a general rule, it always helps to clear out cheese or other food remnants as best you can and check with your local recycling servicer before tossing it in the bin.

“We ask that customers please help keep food and liquids out of recycling bins,” Reed said, “by cleaning and shaking out all food containers, and completely emptying all cans and bottles.”

But how messy is too messy? Guidelines aren’t always clear on this, with many local jurisdictions using somewhat subjective phrases like “lightly soiled” or “greasy” when describing the difference between what’s acceptable and what isn’t.

According to the same WestRock study , the average grease content in pizza boxes currently found in the recycling stream (1-2% by weight) isn’t enough to cause significant “strength loss” in the resulting paper made from recovered fibers. This suggests that even if a box has a few small grease stains, its impact on the filtering and binding phases of the recycling process should be minimal.

If you’re dealing with a pizza box that’s a bit more messy than that, a common tip is to separate and recycle the “upper” portion of the box (the side that didn’t come in contact with the pizza) while disposing of the bottom half. This way, at least some of the box will go back into the recycling stream.

And if composting is an option where you live, it can serve as a great backstop for food-soiled paper products, like greasy pizza boxes. According to a 2023 survey conducted by BioCycle, nearly 15 million U.S. households have access to a curbside composting program, representing a small but growing share (12%) of residences.

Through Recology, San Francisco residents have had access to curbside composting since 2001.

“We tell customers: If a pizza box or other food container is greasy, and your city allows customers to place food-soiled paper in curbside composting bins, place the greasy box in your composting bin (without the round plastic ‘pizza saver’),” Reed said. “Curbside composting keeps materials out of landfills, reduces methane emissions, and helps local farms grow more healthy food and save water.”

So, the next time you plan to get a fresh pie from your go-to spot, remember to check your local recycling guidelines to make sure you aren’t throwing away a perfectly good box or holding up the recycling process with a super greasy one.

This article was produced and syndicated by MediaFeed.org .

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