When cooking foods sous vide, you need more than an immersion circulator to keep the water at a consistent temperature; you also need a way to vacuum seal the food. Vacuum sealers and the special single-use bags they require can be pricey, so Ziploc plastic bags make the perfect alternative — as long as you use them safely.

When picking a plastic bag, make sure they are microwave-safe, which means they’re safe for sous vide, too. Inexpensive bags may contain harmful BPA and phthalates, which can leach out of the bags when heated, so opt for reputable brands like Ziploc and Glad made from polyethylene plastic (PEP) with no PVC or BPA.

Choosing a sturdy zip-top plastic bag is essential, as the real enemy of safe sous vide is an unintentional exposure to air, since that makes for a higher risk of bacterial growth. By safely doing sous vide with a zip-top bag, you’re choosing not only the cheaper option, but also the more sustainable one, since you can reuse them.