Proper washing of lettuce can get rid of many invisible contaminants, such as pesticides and bacteria, as well as the visible ones, such as dirt and insects. The best way to wash lettuce is to rinse the separated leaves in cold water until there is not any visible dirt on any of it. Once it is washed, you can use it immediately or dry it off and store it in the refrigerator for a few days.
In the some countries, lettuce that has been marked as ready to eat has met the requirements specified by governmental agencies, and should be clean enough to eat; however, experts disagree on whether you need to wash lettuce that has been pre-washed or not. Concerns about outbreaks of Escherichia coli (E. coli) outbreaks due to improperly cleaned lettuce have prompted many people to carefully clean this and all lettuce before they eat it, despite claims that it is safe to consume straight from the bag. This lettuce is usually in small pieces and can be placed in a bowl of cold water, swirled around, and then removed and drained.
Preparing to wash lettuce depends partly on what kind of lettuce you have. If you have leaf lettuce such as Romaine, you should cut off the bottom section of the leaves, which includes the roots and the part of the plant where the leaves all come together. Gently separate all of the leaves and drop each one into a bowl of cold water, where you should leave them for at least 30 seconds. Swirl the leaves around in the water and lift them out, using a gentle stream to rinse off any debris that might still be clinging to them.
To wash lettuce that has leaves growing in a tight head, such as iceberg, first use a small, sharp knife such as a paring knife to cut out and remove the core from the bottom of the head. Break the leaves apart and drop them all into a large bowl of cold water, swishing them gently. Leave them for about a minute, which is enough time for sand and dirt to fall off, then lift the leaves out, rinsing them off as you do so to remove any remaining dirt.
If you have a salad spinner, wash lettuce by first placing the colander piece, which is the bowl with holes, into the bowl section of the spinner, where it should snap or lock into place. Fill the spinner bowl with cold water and then place the separated lettuce leaves into the cold water. Stir gently to make all of the sand and dirt fall down into the water, away from the lettuce. Lift out the colander, pour off the dirty water, and put the colander back in place. Put the lid on the spinner and turn the handle to spin off any remaining water and dirt, and your lettuce is ready to use.