So if my bottle of water is empty i have to restart the game?
An empty bottle isn't a problem, but you have to fill it with a flammable liquid—which you won't find in the city. Then you need to insert a rag to act as a fuse. After that, you can throw it by hand. You’ll also need something to light it with, though simply having the item in your inventory is enough. In principle, it should be doable without an incendiary device, but perhaps it really would be better to start over from the beginning. With a bit of planning, you can even get past the cornfield without using any ammo.