Should You Really Be Washing and Reusing Your Zip-Top Bags?

Although disposable storage bags are so handy, it can be  wasteful to use a zip-top plastic baggie just once and then throw it away. But, in the name of being environmentally conscious, is it actually safe to wash and reuse the plastic bags?

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The short answer: Yes, but with “prudence,” says Martin Bucknavage, an expert in food safety in the Penn State Department of Food Science. “If one stored raw meat, poultry, or fish in it, it is probably not ideal to rewash because the potential pathogens that may be present on the meat may be difficult to remove.”

You also shouldn’t reuse it if it held anything else that could harbor microbes like rotten produce or moldy cheese.

It can be difficult to wash away all the very tiny pieces of food from a dirty bag, says Bucknavage. “But we do recognize the cost of such bags and in today’s world of minimizing waste, especially plastic waste, it is understandable that people do want to reuse them.”

When Is It Safe to Reuse Zip-Top Bags?

Brian Hedlund, a microbiologist from the University of Nevada, Las Vegas, says it’s safe to reuse zip-top bags in certain conditions.

“To my knowledge, Ziploc bags are sterile on the inside because they are heated to 180 to 240 Celsius during production. I've tested this myself a few times to confirm,” he says. Bags are no longer sterile once they’ve been used, but certain factors determine whether they can be used again.

“It's perfectly fine to reuse clean Ziploc bags for dry goods, since the water activity is too low to allow microbial growth (for the most part),” Hedlund says. “I would shy away from reusing the bags for non-dry perishables that aren't frozen. I would also avoid reusing Ziploc bags that are in bad condition mainly to limit ingestion of micro and nanoplastics.”

How to Wash Zip-Top Bags

If you’re going to reuse zip-top bags, don’t just give them a cursory rinse under running water. Make certain you clean and dry them well. A spokesperson for Ziploc told us that Ziploc brand bags are reusable if they have not stored raw meat, fish, eggs, or any foods that can trigger allergies.

The company suggests adding some warm water and a drop of antibacterial dish soap to the bag, zipping it shut, and sloshing the water around inside. The company does not recommend turning the bags inside out during cleaning because this might rip the seams.

In most cases, a bag can be used over and over until it tears, the seal doesn’t work any longer, or you can’t clean it successfully.

“They should be reusable until the integrity of the plastic has worn through,” says microbiologist Jason Tetro, host of the Super Awesome Science Show and author of The Germ Code and The Germ Files. There is no hard and fast limit or number of times a bag can be reused,  “as no one person will use the bags in the same way.”