Many busy families see “pre-washed” on a package of grapes and assume the fruit is completely ready to eat. But that label does not mean the grapes are sterile or guaranteed to be free from every contaminant. Processing can remove visible dirt, dust, and some surface residue, but the grapes may still be exposed to bacteria or other contaminants afterward.

During packaging, transportation, and shopping, grapes can be handled by multiple people before reaching your kitchen. Because they are normally eaten raw, giving them another rinse at home is a simple extra precaution. The good news is that washing them takes only seconds. You do not need special products, soap, or expensive produce cleaners. But there is one important mistake you should avoid when washing grapes—and it has nothing to do with how you rinse them.