I tend to wash them in slightly soapy water, then rinse them off with bottled water. With the fruit on the beach, as they have been handling it with their hands after it has been peeled, I tend to swill it with bottled water. However, if you are grape eating off the street then you wont have anywhere to wash the grapes apart from the bottled water, and in my opinion that is not enough, although it is better than using no water at all.