Preheat an outdoor grill for medium heat and lightly oil the grate. Layer 2 sheets of aluminum foil on a work surface.
Toss together green beans and olive oil in a bowl until coated; season with salt and pepper. Place mixture on top of the prepared sheets of foil. Add water, and bring the edges of the foil over the vegetables, sealing to create a pouch.
Place the foil pouch on the preheated grill and cook until beans are tender, about 15 minutes.