There’s nothing quite as disappointing as reheating a slice of pizza in the microwave only to find it’s turned into a rubbery, chewy mess. The microwave, while convenient, has a reputation for zapping moisture out of food, leaving once-delicious leftovers dry and unappetizing. But what if there was a simple trick to prevent this culinary tragedy? Enter the humble cup of water—a game-changer for microwave pizza reheating.

The science behind this hack is straightforward. Microwaves heat food by exciting water molecules, but they don’t discriminate between the moisture in your pizza and the moisture in the surrounding air. As a result, the pizza’s edges and crust often dry out before the center is properly warmed. Placing a cup of water in the microwave alongside your pizza introduces additional moisture into the environment. The water absorbs some of the microwave’s energy, creating steam that helps keep the pizza’s surface from hardening.

Not all cups of water are created equal, though. For best results, use a microwave-safe glass or ceramic cup filled about halfway with room-temperature water. Avoid using plastic containers, as they can warp or release unwanted chemicals when heated. The size of the cup matters too—a standard coffee mug works well for a slice or two, while a larger cup may be needed for multiple slices or a whole pizza.

Timing is another critical factor. Most microwaves will reheat a slice of pizza perfectly in about 30 to 45 seconds when paired with the water cup method. The exact time depends on your microwave’s wattage and the thickness of the pizza. Start with shorter intervals and check the pizza’s temperature to avoid overheating. The goal is to warm the pizza evenly without making it soggy or drying it out.

This trick isn’t just limited to pizza—it works wonders for other microwave-reheated foods prone to drying out, like bread, pastries, and even certain meats. The principle remains the same: the added moisture from the water cup helps maintain the food’s texture and prevents it from becoming tough or leathery. It’s a small step that makes a big difference in preserving the quality of your leftovers.

Some people take this method a step further by covering the pizza with a damp paper towel. While this can help retain moisture, it sometimes leads to a soggier crust. The water cup method strikes a better balance, keeping the pizza soft without sacrificing its structural integrity. Experimentation is key—every microwave behaves slightly differently, so it may take a try or two to perfect the technique for your specific setup.

Beyond practicality, this hack speaks to a larger truth about microwave cooking: small adjustments can dramatically improve results. Microwaves are often maligned for producing subpar food, but the reality is that they’re incredibly powerful tools when used correctly. Understanding how they work and making minor tweaks—like adding a water cup—can elevate your reheating game from mediocre to magnificent.

Next time you’re faced with a cold slice of pizza, don’t resign yourself to a disappointing meal. Reach for a cup of water, pop it in the microwave alongside your pizza, and enjoy a slice that’s nearly as good as fresh. It’s a simple, no-fuss solution that proves sometimes the best kitchen hacks are the easiest ones.