Barrels are one of the oldest forms of containers. Barrels are traditionally made from wood slats with metal straps placed around the wood to hold the slats tightly together. Because of the construction of barrels, leaks are almost inevitable. To fix a leaking barrel there are two different methods to use. Soaking the barrel in water will eliminate smaller leaks, while larger leaks require a filler of some kind.
Remove any objects inside the barrel and dispose of any water present inside the barrel. Move the barrel to a dry, dirt- and grass-free location, such as on a patio, inside a garage or in a driveway.
Place the barrel inside the dustbin or other large container. Fill the container with water from a hose until the barrel is completely submerged. Place a large rock or other weight on top of the barrel to keep it from floating to the surface of the water. Leave the barrel inside the water for about one week. This will cause the wood to swell, reducing the number of leaks inside the barrel. This method will not stop all leaks, however.
Remove the barrel from the water. Dry the outside of the barrel with towels. Fill the inside of the barrel with water. Watch the barrel to see if any leaks remain. If some leaks still remain, empty the barrel and allow to dry for 24 hours. Mark the location of the leaks with a wax pencil.
Put on safety goggles and work gloves. Fill the marked locations with mastic. Use a putty knife to press the mastic into the cracks from the inside. Smooth the mastic over the gap on the inside of the barrel. Apply a second layer of mastic to the outside of the barrel to seal the crack from the other side. Repeat for any other cracks or gaps on the surface of the barrel. Allow the mastic to dry for 24 hours.
Apply a bitumen seal to the entire inside of the barrel with a paintbrush. Allow the seal to dry for 24 hours. Fill the bucket with water once more. If any leaks still remain, apply another coat of seal to the interior of the barrel. Allow to dry for 24 hours.
Fill the bucket with clear water. Allow the water to sit inside the bucket for 24 hours. Pout the water out before using the bucket for any purpose. This soaking process eliminates some of the toxins from the seal, making it safe for plant and fish use.
Fix large leaks with a wedge. Widen the hole slightly with a chisel, until it is about 2 inches across. Make a small piece of wood large enough to slip inside the hole. Hammer the wedge inside the hole. Break off any wood that sticks above the hole with a sharp knife and hammer.