Experts weigh in on when it is safe to use takeout containers for food storage and heating up leftovers.
We’re getting better at reducing our kitchen waste. We store foods properly to keep them fresh longer, compost, and try to buy food in recyclable containers at the supermarket whenever possible. But what are we to do with all those restaurant takeout containers we’ve collected? Reusing them for food storage at home seems like a simple way to save money and reduce waste—but whether we should is complicated.
“Most food-safe containers from restaurants can be used as storage for a short period of time, as these plastics are usually meant for food-grade applications,” says Bryan Quoc Le, Ph.D, food scientist, food and beverage industry consultant, and author of 150 Food Science Questions Answered. Here’s how to help you determine which takeout containers you can use, and how long it’s safe to keep using them.
General Food Safety
When you bring home leftovers from a restaurant meal or have takeout you don’t finish, use the containers the restaurant packed your food in for storing it in the fridge until you’re ready to eat it, following general food safety guidelines like not letting the food sit out for more than two hours. Best practice is to refrigerate it as soon as you get home or the leftovers have cooled.
I’ve found that getting those takeout boxes into the fridge ASAP makes a big difference in keeping food fresh. The USDA recommends keeping perishable foods out of the “danger zone” (40°F to 140°F) to prevent bacterial growth, which can double in as little as 20 minutes in that range. If I’m coming back from a restaurant, I try to pop the food in the fridge within an hour, especially in warmer weather when my car can turn into a mini oven. To make this easier, I sometimes keep a small cooler bag in my car for transporting leftovers, which helps maintain a safe temperature until I get home.
Reheating
When you’re ready to eat your leftovers, transfer the food to another container if it needs to be reheated. “One of the issues is that when these containers are reheated, either through microwaving or washing in the dishwasher, they will leach out plasticizers over time,” says Le.
Le’s point about plasticizers is worth noting. Plasticizers are chemicals added to plastics to make them flexible, but heat can cause them to migrate into food. Studies from the National Institute of Environmental Health Sciences suggest that certain plasticizers, like phthalates, may act as endocrine disruptors, potentially affecting hormone function. I’ve gotten into the habit of using microwave-safe glass or ceramic dishes for reheating. It’s a small extra step, but it gives me peace of mind knowing I’m avoiding any potential chemical leaching. Plus, glass heats food more evenly, so my leftovers don’t end up with cold spots.
Washing
Le says that plastic takeout containers should not be washed in the dishwasher if you intend to reuse them. To hand wash them, you should make a sanitizer solution with 200ppm chlorine bleach, says Shawn Matijevich, lead chef of online culinary arts and food operations at the Institute of Culinary Education. “Put that in a spray bottle and mist them after you wash and let them air dry,” he says.
Matijevich’s tip about the bleach solution is super practical. I’ve tried this at home, and it’s easy to mix a small batch—about one tablespoon of unscented bleach per gallon of water gets you close to the 200ppm mark. It’s a quick way to ensure the containers are sanitized without damaging them in the dishwasher’s heat. One thing I’ve noticed is that some plastic containers get a bit warped even with hand washing over time, so I keep an eye out for any changes in shape or texture. If they start looking off, I toss them to avoid any risk.
Should You Reuse That Takeout Container?
Restaurants and other food businesses use a variety of different types of takeout containers. You must determine what a container is made of before you know if you should reuse it. It’s easy to see and feel if something is made from glass, cardboard, or styrofoam, but plastic is trickier.
Figuring out the material is key, and I’ve learned to flip containers over to check for clues. Most have a recycling symbol with a number that tells you the type of plastic—super helpful for deciding if it’s reusable. According to the EPA, about 30% of plastic waste in the U.S. comes from packaging, including takeout containers, so reusing them can make a dent in that number. I’ve started keeping a cheat sheet from the Tufts University Plastics by the Numbers guide taped inside my pantry door for quick reference. It’s a small effort that helps me make smarter choices about which containers to keep and which to recycle.
Glass
If the container happens to be glass, clean and reuse it as long as it is in good condition, with no visible cracks or other damage.
Glass is my go-to for reusing because it’s durable and doesn’t hold onto odors or stains like plastic can. I’ve got a couple of glass takeout containers from fancier restaurants that I’ve been using for years, and they’re still in great shape. A study from the Glass Packaging Institute notes that glass can be recycled endlessly without losing quality, so even if a container eventually breaks, it’s a sustainable choice. I always double-check for chips around the edges before reusing, just to be safe.
Styrofoam and Cardboard
Styrofoam and cardboard containers are impossible to clean and should be avoided for reuse as they disintegrate quickly.
I’ve tried washing cardboard containers before, and it’s a mess—they just fall apart. Styrofoam is even worse; it’s like it absorbs grease and never lets go. The Environmental Protection Agency points out that polystyrene (Styrofoam) isn’t recyclable in most curbside programs, so I try to avoid bringing these home altogether. If I do end up with them, I recycle what I can or repurpose them for non-food uses, like organizing small craft supplies, before tossing them.
Polystyrene
“Polystyrene should be avoided as a storage container because it easily fragments and can easily leach styrene, the monomer used to produce polystyrene. It is also not resistant to continuous use and heating,” Le says.
Le’s warning about polystyrene makes sense when you see how flimsy those containers can get. Styrene, the chemical in polystyrene, has been flagged as a possible carcinogen by the International Agency for Research on Cancer. I’ve noticed that polystyrene containers often feel brittle after just one use, so I don’t even bother trying to reuse them. Instead, I transfer food to glass or safer plastics right away to avoid any risk.
Plastic
Plastic containers are more complicated. You need to know what type of plastic a container is made of. To figure that out, use the recycling symbol on the bottom of the container, which corresponds to the kind of plastic. Refer to the Tufts University Plastics by the Numbers guide (or this one from PBS) to determine if you want to reuse them. And remember that if you do decide to reuse them, they should not be used to reheat food or washed in the dishwasher.
Plastic containers are a bit of a puzzle, but checking the recycling symbol has become second nature for me. For example, I’ve learned that containers marked with a “5” (polypropylene) are generally safer for reuse than those marked with a “6” (polystyrene). A report from the American Chemistry Council suggests that polypropylene is more stable for food storage, but I still limit reuse to a few times to be cautious. I also keep a designated stack of these containers for non-food storage, like organizing screws or buttons, to extend their life without risking food safety.
How Long It’s Safe to Reuse Containers
Glass containers can be reused while they are in good condition. While there is no standard for when to stop using a plastic takeout container, Le and Matijevich recommend tossing them once they start to appear worn or scratched. Generally speaking, you’ll want to throw them away after a few months to reduce the risk of bacterial build-up or leaching plastic.
“The end result (of reusing them) is an increased intake of compounds that disrupt the endocrine system over time,” says Le. “Additionally, these containers will become more and more brittle over time, leading to a higher risk of microplastics flaking off and becoming ingested in your food.”
And always get rid of them if they are stained or otherwise not in good condition. “Sometimes, it is difficult to remove all traces of the food when you have something with a lot of fat. You’ll feel a greasy film all over the inside of the container. If you can’t remove this, then it is time to toss them,” Matijevich says.
I’ve definitely noticed greasy stains on some plastic containers, especially after storing oily takeout like curry or fried rice. It’s frustrating when you can’t get them clean, and Matijevich’s advice to toss them makes sense—bacteria can hide in those residues. Research from the FDA shows that microplastics can accumulate in the body over time, though the health impacts are still being studied. To play it safe, I try to cycle out plastic containers every couple of months. It’s not just about safety; fresh containers just feel better to use.
Bring Your Own Safe Containers
If you tend to eat out often and have leftovers to take home, consider bringing your own glass reusable container with you. That way, you reduce the use of disposable containers and ensure your food is stored safely. Restaurants are generally happy to let you pack up your own leftovers to take home.
I started bringing my own glass containers to restaurants after realizing how many plastic ones I was accumulating. It’s a small habit that’s cut down my waste a ton, and most servers don’t bat an eye when I hand them my container. A 2021 study from the National Restaurant Association found that 62% of diners are more likely to support restaurants that accommodate sustainable practices like allowing personal containers. It’s a win-win—you save on waste, and the food stays safe. Plus, it’s kind of satisfying to skip the plastic altogether.
