Lettuce being rinsed in steel sieve in kitchen.
Food - Drink
Should You Be Washing Pre-Washed Lettuce?
We always want to make sure before cooking or eating any food that it is sterile, but we can rest assured knowing that the produce industry standards for cleaning vegetables are very stringent. Vegetables are cleaned several times from farm to grocery store for everything from dirt and bugs to bacteria, parasites, and other microbes.
The biggest reason you shouldn’t wash pre-washed lettuce is that the cleaning process you go through in your kitchen is unlikely to be as stringent as the cleaning process that the lettuce has already gone through. If any germs survived the professional treatment, it is unlikely that running the lettuce under cold water will yield any benefit.
You also run the risk of potentially adding bacteria from around your kitchen to the lettuce — completely negating the intended purpose. To quote Jean de la Fontaine, "A person often meets their destiny on the road they take to avoid it," so if you’re still concerned, it’s probably best just to stir-fry it.