If you’re not sure whether or not it’s time to replace your sponge, err on the side of caution and get a new one. After all, they’re relatively inexpensive and easy to find. Plus, it’s better to be safe than sorry when it comes to cleanliness. We asked Jeri Fritz of Highland Park Housekeeping how she knows when to replace sponges for her teams. According to Jeri, here are a few signs that it’s time to say goodbye to your sponge.

4 Signs It’s Time to Get Rid of Your Sponge

The sponge is visibly discolored or stained

“Usually, you can tell if a sponge is ready to be replaced just by looking at it,” Jeri says. “Stains that come from washing dishes or cleaning up messes should wash out relatively easily. If a sponge is keeping stains even after being throughly rinsed, it’s ready to be changed out with a fresh one.”

The sponge has developed a sour smell

“Even if a sponge looks fine, you can tell it’s old by the smell,” Jeri says. “The smell can often be more obvious than the stains.” Like all other fabrics that stay wet for an extended period of time, sponges can develop mold and mildew. If you start to sense a seriously sour smell from your sponge, immediately throw it away and replace it. It will keep your kitchen smelling fresh—and it avoids guests eating from forks scrubbed with a moldy sponge.

The sponge is falling apart or disintegrating

If you’re a clean freak who uses a lot of elbow grease, your sponge might start falling apart before it shows any other signs of aging. Wear and tear on a sponge just makes it less effective, so replace your sponges before they whittle down into nothing.

You can’t remember the last time you replaced your sponge

If you’re reading this article and wondering whether or not you’ve ever replaced your sponge, that’s a sign it’s probably time to do so. “Every two weeks to a month is plenty,” Jeri says. “It just depends on how often you use your sponge and what you use it for. If you cook a lot and scrub pots and pans often, you’ll probably have to replace your sponge sooner than somebody who usually opts for takeout.” Before you start dragging your feet on the way to the sponge store, consider this: sponge shopping can be fun. Sponges come in so many shapes, colors, and even characters, so pick one that you’ll be excited to use. It’s also a good idea to buy at least two sponges at a time so you can keep a back up sponge under your sink. That way, when you notice one of the signs described above, you’re ready to replace your musty sponge with a fresh one.

How to Make Your Sponge Last Longer

Keep your sponge in a well-ventilated area. Do not leave your sponge in the bottom of your sink or stuffed tightly into a cleaning caddy. Sponges, like all fabrics, need air to ventilate, or they will grow mildew and mold, even after just a few uses. Consider purchasing an inexpensive sponge holder that attaches to the side of your sink and helps your sponge dry quickly after use.Make sure to always choose the appropriate sponge for the job. If you’re scrubbing a crusty cookie sheet, opt for a scrubber sponge instead of a soft sponge. This will prevent you from overusing the sponge and running it down too soon.