When you spot a juicy looking apple or bright red strawberry, it can be tempting to pick it up and take a big bite. But, before you eat or cook with any fruits and vegetables, you need to wash them.

Here’s why.

“Fruit and vegetables are a staple in a healthy diet, but fresh produce can harbor bacteria, fungi, and other microbes in addition to trace amounts of chemicals,” said registered dietitian nutritionist Gina McArdle, RDN, LDN, Geisinger Community Medical Center. “Washing fruit and vegetables helps remove dirt, bacteria, garden pests and residual pesticides.”

Although washing produce doesn’t completely remove or kill all of the potential microbes on them, rinsing fresh fruit and vegetables under running water does reduce the number of microorganisms.

“Thoroughly wash your produce under running water, rubbing vegetables and fruit briskly with your hands,” McArdle said. “If you’re washing something with a hard rind or firm skin, like a melon or cucumber, scrub it with a vegetable brush.”

In order to ensure your fruit and vegetables are clean, it may be tempting to think about using soap, detergent or bleach solutions, but you shouldn’t – many types of fresh produce are porous and could absorb them, possibly changing their taste and safety.

You should wash produce even if you don’t plan to eat the rind or skin.

“Bacteria and dirt on the outside of a fruit or vegetable can transfer to the inside if you cut or peel it,” McArdle said.

To wash leafy green vegetables, separate and individually rinse leaves and throw away any torn or bruised leaves. To make cleaning leafy greens easier, try immersing them in a clean bowl of cold water for a few minutes – this loosens any sand and dirt on the leaves. Blot them dry with paper towels or use a salad spinner to remove excess moisture.

Clean apples, cucumbers, and other firm produce by washing them and peeling to remove any waxy preservative on their skin. When it comes to plums, peaches, and other soft fruits, wash them under running water and dry with a paper towel.

When you buy berries, cherries and grapes, store them unwashed until you’re ready to eat them. Gently wash them with cool water right before eating them.

If you buy pre-cut, bagged, or packaged produce in packaging that says it’s pre-washed and ready to eat, you can eat or cook with it without washing it again. Just make sure it doesn’t come in contact with unclean utensils or surfaces to prevent cross contamination that can lead to food poisoning.

“Before preparing fresh produce, always make sure you wash your hands with soap and water,” McArdle said. “And make sure any cutting boards, utensils, or counter tops involved in your food prep are clean before you peel and slice produce.”