To build a rain barrel, attach a tap to a plastic garbage can, create inflow and overflow holes through the can, seal the barrel, and position it. You need a tap, a drill, metal washers, rubber washers and a big plastic garbage can to complete this task. A hose clamp, a landscaping fabric and watertight sealant are also handy in this task.
To attach the tap on the can, first locate a suitable spot close to the barrel's bottom, and drill a hole through the spot so the hole is slightly smaller than the tap. Put the metal washer over the tap threads, and add the rubber washer. Cover the rubber washer with the sealant, align the threads with the hole, and turn the tap clockwise to secure it in place. Once the sealant is dry, fix the other two washers over the protruding tap in the barrel the same way you did with the first washers, but start with a rubber washer this time. Then, clamp the tap onto the barrel.
Next, drill an inflow hole through the can's lid. Create an overflow hole just close to the lid. To seal the barrel, remove the lid, cover the barrel's opening with the landscaping fabric, replace the lid, and cut a hole in the fabric to allow water inflow, taking care to align it with the hole in the lid. Finally, build the barrel stand at the downspout, place the barrel on the stand, and align the inflow hole with the downspout.