Empty tin cans are a throwable item that can be obtained from most areas on the map and by eating Canned Goods. Selecting the empty tin can and firing, much like with Empty Whiskey Bottle and Empty Soda Can, will cause your character to throw the can grenade-style a certain distance depending on the amount of time you held the fire key down. When hitting a surface near zombies, the can will attract their attention, and they will (typically) begin to investigate the noise. This item is usually used as a means of escaping areas while surrounded by zombies, but has also been used for breaking hospital windows and for distracting other Survivors.
The empty tin can is also used for Drinking from ponds. Simply walk into a pond, and select "Drink" on the Can.
You can clean infected water with it, you need: empty tin can, fireplace and water bottle.