Rain barrels can be a great way to store water for outside use, but cold or freezing weather can be harmful to a plastic rain barrel's durability. Expanding water can result in a hairline crack, which will cause the barrel to leak. Before you decide to buy a new rain barrel, however, try a simple, inexpensive repair job.
Empty the rain barrel of all water. Clean away any dirt, dust or debris from the outside and inside of the barrel using a hose and clean rag.
Rough up the area around the crack by rubbing coarse sandpaper over the plastic barrel until the area is visibly sanded. This roughness will help the silicone caulk stick to the plastic surface.
Insert a small drill bit into a cordless drill. Drill a small hole at each end of the crack to prevent the crack from growing longer. Wipe away all sanding and plastic debris using a clean, damp rag. Allow the barrel to completely dry before continuing.
Cut out a piece of scrap fabric that is slightly larger than the height and width of the hairline crack.
Load a tube of caulk into the caulking gun.
Apply a thick bead of silicone caulk along the hairline crack. Caulk the entire length of the crack, using a generous amount of caulk. Place the fabric over the caulked area and press it into the caulk, moving the excess caulk outward with your fingers until the fabric is flush with the barrel. This will help to "weld" the caulk to the side of the barrel, preventing it from peeling away.
Caulk along the hairline crack in the inside of the barrel. Allow the caulk to dry completely before using the rain barrel.