Place the elderberries in a large colander. Wash and sort a small amount at a time; otherwise, the berries will crush each other under their own weight. A layer no deeper than 2 to 3 inches at the bottom of the colander is sufficient.
Pick out any stems or leaves mixed in with the elderberries. Grasp individual berries gently, and twist them from the stem. Pulling may crush the berry.
Dispose of badly crushed and discolored berries. Slight crushing that occurs during stem removal is OK. Only dispose of those that are already crushed on the stem.
Run cool water over the elderberries. Swish the berries around gently with your hand as the water runs over them.
Drain the elderberries completely in the colander. Use the cleaned berries immediately.